Non-controlling Interests (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Non-controlling Interests [Abstract]
Net income attributable to common shareholders		$ 36,079	$ 35,272	$ 151,678	$ 75,308
Increase in equity for conversion of operating partnership units				16	0
Decrease in additional paid-in capital for purchase of remaining non-controlling ownership interests in two consolidated joint ventures (1)	[1]			(9,480)	0
Change in common shareholders' equity and net transfers from noncontrolling interests				$ 142,214	$ 75,308

[1] Refer to Note 5, "Acquisitions, Dispositions, and Impairment," for further discussion of acquisitions.