Equity - Changes in AOCI/L by Component (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 983,465
Other comprehensive (loss) income, net of tax	$ (56,276)	$ (1,057)	(25,559)	$ 794
Ending balance	921,432		921,432
Interest Rate Swaps
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	12,597	(3,977)	2,483	(1,409)
Change in AOCI/L before reclassifications to income	4,005	(3,528)	13,370	(6,921)
Reclassifications from AOCL/I to income	(321)	1,398	428	2,223
Other comprehensive (loss) income, net of tax	3,684	(2,130)	13,798	(4,698)
Ending balance	16,281	(6,107)	16,281	(6,107)
Defined Benefit Pension Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(5,805)	(5,749)	(5,861)	(5,797)
Change in AOCI/L before reclassifications to income	0	0	0	0
Reclassifications from AOCL/I to income	55	49	111	97
Other comprehensive (loss) income, net of tax	55	49	111	97
Ending balance	(5,750)	(5,700)	(5,750)	(5,700)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	25,433	(38,106)	4,886	(42,477)
Change in AOCI/L before reclassifications to income	295	1,024	20,842	5,395
Reclassifications from AOCL/I to income	(60,310)	0	(60,310)	0
Other comprehensive (loss) income, net of tax	(60,015)	1,024	(39,468)	5,395
Ending balance	(34,582)	(37,082)	(34,582)	(37,082)
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	32,225	(47,832)	1,508	(49,683)
Change in AOCI/L before reclassifications to income	4,300	(2,504)	34,212	(1,526)
Reclassifications from AOCL/I to income	(60,576)	1,447	(59,771)	2,320
Other comprehensive (loss) income, net of tax	(56,276)	(1,057)	(25,559)	794
Ending balance	$ (24,051)	$ (48,889)	$ (24,051)	$ (48,889)