Stockholders' Equity (Details) - Changes in AOCL/I by Component - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Beginning Balance	$ 60,878	$ (132,400)	$ 161,171
Changes during the period:
Change in AOCL/I before reclassifications to income	45,871	(10,001)
Reclassifications from AOCL/I to income during the period	5,320	4,720
Other comprehensive (loss) income, net of tax	51,191	(5,281)	(23,232)
Ending Balance	983,465	60,878	(132,400)
AOCI Attributable to Parent
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Beginning Balance	(49,683)	(44,402)	(21,170)
Changes during the period:
Other comprehensive (loss) income, net of tax	51,191	(5,281)	(23,232)
Ending Balance	1,508	(49,683)	(44,402)
Interest Rate Swaps
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Beginning Balance	(1,409)	(3,079)
Changes during the period:
Change in AOCL/I before reclassifications to income	(1,492)	(2,902)
Reclassifications from AOCL/I to income during the period	5,384	4,572
Other comprehensive (loss) income, net of tax	3,892	1,670
Ending Balance	2,483	(1,409)	(3,079)
Defined Benefit Pension Plans
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Beginning Balance	(5,797)	(4,832)
Changes during the period:
Change in AOCL/I before reclassifications to income	0	(1,113)
Reclassifications from AOCL/I to income during the period	(64)	148
Other comprehensive (loss) income, net of tax	(64)	(965)
Ending Balance	(5,861)	(5,797)	(4,832)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Beginning Balance	(42,477)	(36,491)
Changes during the period:
Change in AOCL/I before reclassifications to income	47,363	(5,986)
Reclassifications from AOCL/I to income during the period	0	0
Other comprehensive (loss) income, net of tax	47,363	(5,986)
Ending Balance	$ 4,886	$ (42,477)	$ (36,491)