Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period			$ 790,385
Accumulated other comprehensive loss at end of period	$ 810,620		810,620
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period	(171)	$ (247)	(209)	$ (285)
Losses reclassified from net accumulated other comprehensive loss	19	19	57	57
Net current period other comprehensive income	19	19	57	57
Accumulated other comprehensive loss at end of period	$ (152)	$ (228)	$ (152)	$ (228)