XML 90 R74.htm IDEA: XBRL DOCUMENT v3.10.0.1
Stock-Based Compensation Plans - Narrative (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Stock-based Compensation Plans (Textual) [Abstract]      
Cash received from purchase plan purchases $ 7,600 $ 7,100 $ 7,100
Stock-based compensation cost 18,714 18,900 21,073
Unrecognized compensation cost related to stock-based compensation arrangements $ 34,700    
Weighted average period for recognition of cost 3 years 2 months 12 days    
Incentive Plan      
Stock-based Compensation Plans (Textual) [Abstract]      
Shares available for issuance (in shares) 842,532    
Restricted Stock Awards      
Stock-based Compensation Plans (Textual) [Abstract]      
Fair value of shares vested during period $ 15,200 $ 19,200 $ 16,500
Restricted Stock Awards | Maximum      
Stock-based Compensation Plans (Textual) [Abstract]      
Vesting period upon issuance (up to) 5 years    
Employee Stock Purchase Plan      
Stock-based Compensation Plans (Textual) [Abstract]      
Shares available for issuance (in shares) 991,087    
Shares authorized for issuance (in shares) 4,500,000    
Employee stock purchase price in percentage of fair market value 85.00%    
Shares issued to employees (in shares) 148,007 123,448 152,138
Weighted average per share fair value of employee stock purchase rights issued (in dollars per share) $ 15.15 $ 16.51 $ 13.40