Derivative Financial Instruments - Impact of Derivatives on Consolidated Statement of Changes in Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Amount of gain recognized in other comprehensive income (loss)	$ 6,453	$ 2,125	$ 34,718	$ (1,133)
Less: amount of loss reclassified in interest expense	(21)	(2,689)	(2,142)	(8,697)
Total change in other comprehensive income (loss) for unrealized gains (losses) on derivatives, before income tax (expense) benefit	$ 6,474	$ 4,814	$ 36,860	$ 7,564