Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Change in Fair Value Derivative Instruments Designated as Cash Flow Hedges, Income Tax Effect	$ (234)	$ 16,512	$ 0
Reclassification of Realized Loss on Interest Rate Swap Agreements Designated as Cash Flow Hedges, Income Tax Effect	171	423	0
Amortization of net loss on terminated derivative instruments designated as cash flow hedges, net of income tax effect of	$ 0	$ 0	$ 0