Accounting for Derivatives - Effect of Derivative Instruments on Income Statement (Details) - Interest rate swaps - Derivatives designated as cash flow hedges: - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Effect of derivative instruments on results of operations
Pre-tax Gain (Loss) Recognized in Other Comprehensive Income (Loss) on Derivatives	$ (6,100)	$ 846	$ (12,098)	$ (2,283)
Interest expense
Effect of derivative instruments on results of operations
Pre-tax Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss)	$ (2,006)	$ (1,414)	$ (5,697)	$ (3,917)