Redemption of Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended
	Apr. 30, 2017	Mar. 31, 2017	Mar. 31, 2017
Excess of redemption value over carrying value of preferred shares subject to redemption			$ 13,373
Class F Preferred Stock
Preferred stock redeemed (in shares)	16,350,000	16,350,000
Preferred stock, dividend rate (as a percent)		6.625%
Preferred stock, redemption price per share (in dollars per share)	$ 25	$ 25	$ 25
Preferred stock, redemption amount		$ 408,800	$ 408,800
Excess of redemption value over carrying value of preferred shares subject to redemption		$ 13,400