XML 71 R61.htm IDEA: XBRL DOCUMENT v3.8.0.1
Equity - Treasury Stock (Detail) - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Jun. 30, 2017
Equity, Class of Treasury Stock [Line Items]        
Payments for repurchase of common stock $ 173,913,000 $ 0    
2017 Repurchase Program        
Equity, Class of Treasury Stock [Line Items]        
Treasury stock acquired (in shares) 5,000,000.0   1,400,000.0  
Payments for repurchase of common stock $ 173,900,000   $ 50,000,000  
2017 Repurchase Program | Maximum        
Equity, Class of Treasury Stock [Line Items]        
Aggregate authorized amount of common stock to be repurchased       $ 300,000,000
Treasury Stock Associated with Deferred Compensation Plans        
Equity, Class of Treasury Stock [Line Items]        
Treasury stock acquired, value $ 3,300,000 $ 3,200,000    
Common Stock Withheld for Settlement of Employee Tax Liabilities        
Equity, Class of Treasury Stock [Line Items]        
Treasury stock acquired (in shares) 400,000 500,000    
Treasury stock acquired, value $ 13,400,000 $ 17,100,000