Subsequent Events - (Details)
1 Months Ended 3 Months Ended
May 01, 2018
Apr. 30, 2018
USD ($)
$ / shares
shares
Aug. 31, 2017
USD ($)
Mar. 31, 2018
USD ($)
$ / shares
shares
Dec. 31, 2017
USD ($)
Subsequent Event [Line Items]          
Stock repurchase program, remaining authorized repurchase amount       $ 63,900,000  
Stock repurchased during period (in shares) | shares       13,161,065  
Stock repurchased, weighted average price (in dollars per share) | $ / shares       $ 7.88  
Stock repurchase program, authorized amount     $ 250,000,000    
Stock repurchase program, period in force     18 months    
Total debt, gross       $ 3,827,928,000 $ 3,740,651,000
Subsequent Event          
Subsequent Event [Line Items]          
Stock repurchased during period (in shares) | shares   8,061,192      
Stock repurchased, weighted average price (in dollars per share) | $ / shares   $ 7.93      
Stock repurchase program, authorized amount   $ 250,000,000      
Stock repurchase program, period in force   18 months      
Spin-off transaction, stock issuance ratio 0.1        
Master Trust Notes          
Subsequent Event [Line Items]          
Total debt, gross       2,243,210,000 2,248,504,000
Master Trust Notes | Series 2013-1 Class A          
Subsequent Event [Line Items]          
Total debt, gross       $ 123,781,000 $ 125,000,000