Equity - Reclassifications Out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 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	23,390	24,611
Total other comprehensive loss	6,086	19,591
Ending equity balance, value	2,322,607	2,325,736
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss)
Beginning equity balance, value	(156,676)	(139,805)
Other comprehensive loss before reclassifications	8,238	20,170
Amounts reclassified from accumulated other comprehensive loss to:
Total	(2,152)	(579)
Total other comprehensive loss	6,086	19,591
Net current-period Other comprehensive income attributable to noncontrolling interests	(259)	(911)
Ending equity balance, value	(150,849)	(121,125)
Accumulated Other Comprehensive Loss | Reclassification out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense	706	1,801
Other income and (expenses)	(2,858)	(2,380)
Gains and Losses on Derivative Instruments
Accumulated Other Comprehensive Income (Loss)
Beginning equity balance, value	29,549	28,200
Other comprehensive loss before reclassifications	(401)	(11,165)
Amounts reclassified from accumulated other comprehensive loss to:
Total	(2,152)	(579)
Total other comprehensive loss	(2,553)	(11,744)
Net current-period Other comprehensive income attributable to noncontrolling interests	0	0
Ending equity balance, value	26,996	16,456
Gains and Losses on Derivative Instruments | Reclassification out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense	706	1,801
Other income and (expenses)	(2,858)	(2,380)
Gains and Losses on Marketable Securities
Accumulated Other Comprehensive Income (Loss)
Beginning equity balance, value	(48)	(77)
Other comprehensive loss before reclassifications	30	7
Amounts reclassified from accumulated other comprehensive loss to:
Total	0	0
Total other comprehensive loss	30	7
Net current-period Other comprehensive income attributable to noncontrolling interests	0	0
Ending equity balance, value	(18)	(70)
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
Other income and (expenses)	0	0
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss)
Beginning equity balance, value	(186,177)	(167,928)
Other comprehensive loss before reclassifications	8,609	31,328
Amounts reclassified from accumulated other comprehensive loss to:
Total	0	0
Total other comprehensive loss	8,609	31,328
Net current-period Other comprehensive income attributable to noncontrolling interests	(259)	(911)
Ending equity balance, value	(177,827)	(137,511)
Foreign Currency Translation Adjustments | Reclassification out of Accumulated Other Comprehensive Income
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense	0	0
Other income and (expenses)	$ 0	$ 0