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)