Stockholders' Equity of the Company (Details) - USD ($)				1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 30, 2017	Jan. 13, 2017	Dec. 30, 2016	Jan. 31, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2014
Common Stock of the Company [Abstract]
Common stock, shares issued (in shares)				4,427,500	98,351,217		98,351,217		93,219,439
Net proceeds from issuance of common stock (Note 7)				$ 308,800,000			$ 308,832,000	$ 0
At the market stock offering aggregate gross sales price of common stock										$ 300,000,000
Payments of special cash dividends		$ 184,300,000
Dividends declared per common share (in dollars per share)			$ 1.90		$ 0.425	$ 0.375000	$ 0.8	$ 0.725
Payment of special dividend		$ 36,400,000					$ 255,292,000	$ 65,935,000
Series G Cumulative Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, redeemed (in shares)	4,000,000				0		0		4,000,000
Preferred stock dividend rate percentage	6.875%						0.00%		6.875%
Preferred stock, liquidation preference (in dollars per share)	$ 25.00
Preferred stock liquidation preference	$ 100,000,000				$ 0		$ 0		$ 100,000,000
Write off of issuance costs							$ 3,800,000
Common Stock [Member] | Issuance of Equity - at the market offering [Member]
Common Stock of the Company [Abstract]
Common stock, shares issued (in shares)					2,459,165		2,459,165
At the market stock offering aggregate gross sales price of common stock					$ 182,400,000		$ 182,400,000
At the market stock offering remaining amount available for issuance					$ 117,600,000		$ 117,600,000