v3.10.0.1
Derivatives - Additional Information (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Derivatives, Fair Value [Line Items]          
Unrealized gain (loss) on derivatives, net of tax $ 5,662 $ (3,709) $ 21,833 $ (4,473)  
Recognized interest expense on derivatives into earnings, net of tax (422) 340 (1,636) 904  
Derivative assets 24,300   24,300   $ 1,900
Derivative liabilities 1,400   1,400   $ 8,600
Interest rate swaps          
Derivatives, Fair Value [Line Items]          
Unrealized gain (loss) on derivatives, net of tax 5,700 3,700 21,800 4,500  
Unrealized gain (loss) on derivatives, tax expense (2,100) 2,400 (7,600) 2,900  
Recognized interest expense on derivatives into earnings, net of tax 400 300 1,600 900  
Recognized interest expense on derivatives into earnings, tax expense 200 $ 200 600 $ 600  
Additional amount to be classified as an increase to interest expense during next 12 months $ (1,100)   $ (1,100)