Non-controlling Interests (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Non-controlling Interest [Line Items]
Net income attributable to common shareholders	$ 40,893	$ 290,898	$ 446,302	$ 41,730	$ 60,593	$ 37,044	$ 36,079	$ 115,599	$ 819,823	$ 249,315		$ 292,089
Increase in equity for conversion of operating partnership units									290	86		52
Decrease in additional paid-in capital for purchase of remaining non-controlling ownership interests in two consolidated joint ventures									0	(9,480)	[1]	0
Change in common equity and net transfers from non-controlling interests									$ 820,113	$ 239,921		$ 292,141

[1] Refer to Note 7, "Acquisitions, Dispositions, Impairment, and Discontinued Operations," for further discussion of acquisitions.