Equity and Accumulated Other Comprehensive Loss, Net (7.375% Series H Cumulative Convertible Preferred Stock Narrative) (Details) - Series H Preferred Stock and Unit $ / shares in Units, $ in Millions		6 Months Ended	12 Months Ended
	Mar. 26, 2014 USD ($) shares	Jun. 30, 2015 $ / shares	Dec. 31, 2015 USD ($) quarter $ / shares shares	Dec. 31, 2014 $ / shares shares	Apr. 07, 2014 shares
Class of Stock [Line Items]
Preferred stock, shares issued (in shares) | shares	12,000,000		14,600,000	14,600,000	2,000,000
Preferred stock, dividend rate	7.375%		7.375%	7.375%
Gross proceeds from issuance of redeemable preferred stock | $	$ 289.3		$ 353.3
Annual rate of dividend per share (in dollars per share)			$ 1.84375
Preferred Stock, liquidation preference per share/unit			25	$ 25
Preferred stock dividends per share declared (in dollars per share)		$ 0.48655
Preferred stock, redemption price per share (in dollars per share)			$ 25.00
Number of quarters with no dividends triggering voting rights | quarter			6
Shares issued upon conversion | shares			0.9632
Over Allotment Option
Class of Stock [Line Items]
Preferred stock, shares issued (in shares) | shares					600,000