Accumulated Other Comprehensive Loss - Amounts Reclassified from Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax (expense) benefit	$ (5,375)	$ (10,010)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net of tax	215
Interest rate contract | Loss on Cash Flow Hedge | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest expense	215
Tax (expense) benefit	$ 0