Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 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	$ 800,240		800,240
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	(190)	$ (266)	(209)	$ (285)
Losses reclassified from net accumulated other comprehensive loss	19	19	38	38
Net current period other comprehensive income	19	19	38	38
Accumulated other comprehensive loss at end of period	$ (171)	$ (247)	$ (171)	$ (247)