Accumulated OCI, Reclassifications Out of Accumulated OCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 4,130	$ 4,176	$ 7,964	$ 8,281
Income tax benefit	9,560	0	18,931	0
Net of tax	$ (13,567)	$ 175,492	(28,827)	189,389
Amounts Reclassified from Accumulated Other Comprehensive Income [Member] | Interest Rate Swaps [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense			0	264
Income tax benefit			0	(105)
Net of tax			$ 0	$ 159