Accumulated OCI, Reclassifications Out of Accumulated OCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 17,318	$ 17,996	$ 17,449
Income tax benefit	21,973	29,285	27,558
Net of tax	(128,615)	(31,318)	$ (5,561)
Amounts reclassified from accumulated other comprehensive income to: [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax benefit	(201)	(140)
Net of tax	306	214
Amounts reclassified from accumulated other comprehensive income to: [Member] | Interest Rate Swaps [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 507	$ 354