Quarterly report pursuant to Section 13 or 15(d)

Stock-based Expense - Schedule of Stock-based Expense (Details)

v3.10.0.1
Stock-based Expense - Schedule of Stock-based Expense (Details) - $ / shares
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2018
Restricted Stock | Vesting condition 4    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Granted shares of restricted stock (in shares) 0 129,341
Performance-Based Restricted Stock    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Granted shares of restricted stock (in shares)   517,364
Performance-Based Restricted Stock | Vesting condition 1    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Granted shares of restricted stock (in shares) 0 129,341
Number of consecutive trading days required to calculate average price per share (in days)   20 days
Minimum price per common stock for vesting eligibility (in dollars per share)   $ 60.89
Performance-Based Restricted Stock | Vesting condition 2    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Granted shares of restricted stock (in shares) 0 129,341
Number of consecutive trading days required to calculate average price per share (in days)   20 days
Minimum price per common stock for vesting eligibility (in dollars per share)   $ 66.98
Performance-Based Restricted Stock | Vesting condition 3    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Granted shares of restricted stock (in shares) 0 129,341
Number of consecutive trading days required to calculate average price per share (in days)   20 days
Minimum price per common stock for vesting eligibility (in dollars per share)   $ 73.07
Performance-Based Restricted Stock | Vesting condition 4    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of consecutive trading days required to calculate average price per share (in days)   20 days
Minimum price per common stock for vesting eligibility (in dollars per share)   $ 85.24
2010 Equity Incentive Plan | Restricted Stock | Vesting condition 1    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Granted shares of restricted stock (in shares) 163,766 978,444
Vesting period (in years)   3 years
2010 Equity Incentive Plan | Restricted Stock | Vesting condition 2    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Granted shares of restricted stock (in shares) 0 3,600
Vesting period (in years)   1 year
2010 Equity Incentive Plan | Restricted Stock | Vesting condition 3    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Granted shares of restricted stock (in shares) 33,846 33,846