XML 77 R66.htm IDEA: XBRL DOCUMENT v3.10.0.1
Changes in Stockholders' Equity (Narrative) (Details)
3 Months Ended 6 Months Ended
Jun. 30, 2018
USD ($)
$ / shares
shares
Jun. 30, 2018
USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Purchases and retirement of common stock   $ 34,300,000
Stock repurchase program, outstanding balance authorized to be repurchased $ 297,100,000 297,100,000
Stock repurchase program, value of remaining number of shares authorized to be repurchased $ 31,400,000 31,400,000
Open Market Transaction [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock Repurchased and Retired During Period, Shares | shares 534,403  
Purchases and retirement of common stock $ 34,300,000  
Stock Repurchased and Retired During Period, Average Cost Per Share | $ / shares $ 64.14  
December 2016 ASR Program [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock repurchase program, authorized amount $ 265,700,000.0 $ 265,700,000.0