Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended			9 Months Ended						9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Reclassification out of Accumulated Other Comprehensive Income [Member]	Sep. 30, 2013 Reclassification out of Accumulated Other Comprehensive Income [Member]	Sep. 30, 2014 Accumulated Other Comprehensive Income (Loss) [Member]	Sep. 30, 2013 Accumulated Other Comprehensive Income (Loss) [Member]	Dec. 31, 2013 Accumulated Other Comprehensive Income (Loss) [Member]	Dec. 31, 2012 Accumulated Other Comprehensive Income (Loss) [Member]	Sep. 30, 2014 Noncontrolling Interest [Member]	Sep. 30, 2013 Noncontrolling Interest [Member]	Dec. 31, 2013 Noncontrolling Interest [Member]	Dec. 31, 2012 Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income Components [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net						$ 4,880
Amount of gain/loss on interest rate contract reclassfied from AOCI						6,853	2,860
Amount of gain/loss on interest rate contract reclassfied from AOCI for unconsolidated joint ventures						2,340	2,297
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax								3,306	3,020	5,040	1,888	1,313	1,198	2,011	756
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax								(12,564)	(17,294)	(13,954)	(23,952)	6,830	4,672	6,141	1,739
Accumulated Other Comprehensive Income (Loss), Net of Tax	(9,258)		(9,258)		(8,914)			(9,258)	(14,274)	(8,914)	(22,064)	8,143	5,870	8,152	2,495
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax								(1,741)	1,127			(691)	447
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax								(8,478)	3,981			(3,516)	1,776
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent								(10,219)	5,108
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Noncontrolling Interest												(4,207)	2,223
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent								(1,741)	1,127
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent								1,368	6,641
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent								(373)	7,768
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Noncontrolling Interest												(691)	447
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Noncontrolling Interest												711	2,950
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest												20	3,397
Other Comprehensive Income (Loss) Adjustment Foreign Currency Attributable To Parent								7	5
Other comprehensive income (loss), adjustments, attributable to parent								22	17
Other comprehensive income (loss), total adjustments attributable to parent								29	22
Other Comprehensive Income Loss Adjustment Foreign Currency Attributable To Noncontrolling Interest												(7)	(5)
Other comprehensive income (loss), adjustments, attributable to noncontrolling interests												(22)	(17)
Other comprehensive income (loss), total adjustments attributable to noncontrolling interests												(29)	(22)
Gain on sale of marketable securities (Note 12)				1,323			(1,323)
Reclassification adjustment for amounts recognized in net income	$ 2,599	$ 1,740	$ 14,073	$ 3,834		$ 14,073	$ 3,834	$ 9,846	$ 2,660			$ 4,227	$ 1,174