Debt - Credit Facility (Details) - USD ($)		1 Months Ended			6 Months Ended
	Aug. 02, 2016	Jul. 31, 2016	Jun. 30, 2016	Sep. 30, 2013	Jun. 30, 2016	Dec. 31, 2015	Mar. 31, 2013
Line of Credit Facility [Line Items]
Credit facility			$ 142,000,000		$ 142,000,000	$ 0
Senior Secured Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility amount, maximum			800,000,000	$ 800,000,000	800,000,000		$ 500,000,000
Credit facility			$ 142,000,000		$ 142,000,000	$ 0
Until March 2017 | Senior Secured Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate					2.75%
Until March 2017 | LIBOR | Senior Secured Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate				2.75%
March 2017 and Thereafter | Senior Secured Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate					3.125%
March 2017 and Thereafter | LIBOR | Senior Secured Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate				3.125%
Series E Perpetual Preferred Shares
Line of Credit Facility [Line Items]
Preferred stock, dividend rate, percentage			6.35%		6.35%
Subsequent Event | Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Repayments of borrowings on existing credit facility		$ 142,000,000
Subsequent Event | Series E Perpetual Preferred Shares
Line of Credit Facility [Line Items]
Preferred stock, dividend rate, percentage	6.35%	6.35%