Equity - Reclassifications Out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss)
Beginning equity balance, value			$ 2,315,004	$ 2,294,595
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense	$ 21,776	$ 25,048	66,619	75,027
Total other comprehensive loss	22,188	1,323	68,445	5,467
Ending equity balance, value	2,359,105	2,378,427	2,359,105	2,378,427
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss)
Beginning equity balance, value	(111,800)	(136,101)	(156,676)	(139,805)
Amounts reclassified from accumulated other comprehensive loss to:
Ending equity balance, value	(90,220)	(134,886)	(90,220)	(134,886)
Gains and Losses on Derivative Instruments
Accumulated Other Comprehensive Income (Loss)
Beginning equity balance, value	16,857	20,595	29,549	28,200
Amounts reclassified from accumulated other comprehensive loss to:
Ending equity balance, value	10,064	18,203	10,064	18,203
Gains and Losses on Marketable Securities
Accumulated Other Comprehensive Income (Loss)
Beginning equity balance, value	(17)	(63)	(48)	(77)
Amounts reclassified from accumulated other comprehensive loss to:
Ending equity balance, value	(16)	(55)	(16)	(55)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss)
Beginning equity balance, value	(128,640)	(156,633)	(186,177)	(167,928)
Amounts reclassified from accumulated other comprehensive loss to:
Ending equity balance, value	(100,268)	(153,034)	(100,268)	(153,034)
AOCI Including Portion Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss)
Other comprehensive loss before reclassifications	23,568	1,626	72,535	5,825
Amounts reclassified from accumulated other comprehensive loss to:
Total	(1,380)	(303)	(4,090)	(358)
Total other comprehensive loss	22,188	1,323	68,445	5,467
AOCI Including Portion Attributable to Noncontrolling Interest | Reclassification out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense	569	1,869	1,878	5,492
Other income and (expenses)	(1,949)	(2,172)	(5,968)	(5,850)
Gains and Losses on Derivative Instruments
Accumulated Other Comprehensive Income (Loss)
Other comprehensive loss before reclassifications	(5,413)	(2,089)	(15,395)	(9,639)
Amounts reclassified from accumulated other comprehensive loss to:
Total	(1,380)	(303)	(4,090)	(358)
Total other comprehensive loss	(6,793)	(2,392)	(19,485)	(9,997)
Gains and Losses on Derivative Instruments | Reclassification out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense	569	1,869	1,878	5,492
Other income and (expenses)	(1,949)	(2,172)	(5,968)	(5,850)
Gains and Losses on Marketable Securities
Accumulated Other Comprehensive Income (Loss)
Other comprehensive loss before reclassifications	1	8	32	22
Amounts reclassified from accumulated other comprehensive loss to:
Total	0	0	0	0
Total other comprehensive loss	1	8	32	22
Gains and Losses on Marketable Securities | Reclassification out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense	0	0	0	0
Other income and (expenses)	0	0	0	0
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss)
Other comprehensive loss before reclassifications	28,980	3,707	87,898	15,442
Amounts reclassified from accumulated other comprehensive loss to:
Total	0	0	0	0
Total other comprehensive loss	28,980	3,707	87,898	15,442
Foreign Currency Translation Adjustments | Reclassification out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense	0	0	0	0
Other income and (expenses)	0	0	0	0
Noncontrolling Interests
Amounts reclassified from accumulated other comprehensive loss to:
Net current-period Other comprehensive income attributable to noncontrolling interests	(608)	(108)	(1,989)	(548)
Gains and Losses on Derivative Instruments
Amounts reclassified from accumulated other comprehensive loss to:
Net current-period Other comprehensive income attributable to noncontrolling interests	0	0	0	0
Gains and Losses on Marketable Securities
Amounts reclassified from accumulated other comprehensive loss to:
Net current-period Other comprehensive income attributable to noncontrolling interests	0	0	0	0
Foreign Currency Translation Adjustments
Amounts reclassified from accumulated other comprehensive loss to:
Net current-period Other comprehensive income attributable to noncontrolling interests	$ (608)	$ (108)	$ (1,989)	$ (548)