Accumulated OCI, Reclassifications Out of Accumulated OCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 4,203	$ 4,833	$ 12,167	$ 13,115
Income tax benefit	10,403	13,126	29,334	13,126
Net of tax	$ (26,405)	$ (53,874)	$ (55,232)	135,515
Amounts Reclassified from Accumulated Other Comprehensive Income [Member] | Interest Rate Swaps [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense				390
Income tax benefit				(154)
Net of tax				$ 236