Derivative Financial Instruments - Impact of Derivatives on the Statements of Changes in Stockholder's Equity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	$ 10,452
Amount of gain (loss) recognized in other comprehensive income (loss)		$ 8,008	$ (3,901)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	(1,455)
Amount of loss reclassified in interest expense		(11,187)	(17,665)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax	11,907
Total change in other comprehensive income (loss) for unrealized gains (losses) on derivatives, before income tax (expense) benefit	$ 11,907	$ 19,195	$ 13,764