Derivatives Derivatives Pre-Tax Losses (Details) - Designated as hedging instrument [Member] - Interest rate swap [Member] - Cash flow hedging [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on cash flow hedge ineffectiveness, net	$ 0	$ 0	$ 0
Effective portion [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on interest rate cash flow hedges, pretax, accumulated other comprehensive income (loss)	(1,144)	(3,759)	4,159
Effective portion [Member] | Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, loss reclassified from accumulated OCI into income, effective portion	$ (160)	$ (83)	$ 0