Shareholders' Equity - Participating Preferred Shares (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2016 USD ($) market	Sep. 30, 2015
Class of Stock [Line Items]
Cumulative change in value of index based on purchase prices		50.00%
Number of top markets used for purchase price index | market		20
Liquidation preference value | $	$ 470.9	$ 470.9
5.0% Series A Participating Preferred Shares
Class of Stock [Line Items]
Preferred stock, dividend rate, percentage	5.00%	5.00%	5.00%
5.0% Series B Participating Preferred Shares
Class of Stock [Line Items]
Preferred stock, dividend rate, percentage	5.00%	5.00%	5.00%
5.5% Series C Participating Preferred Shares
Class of Stock [Line Items]
Preferred stock, dividend rate, percentage	5.50%	5.50%	5.50%