Preferred Stock (Details) (Mandatorily redeemable convertible preferred units, USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Sep. 28, 2012
Series A Preferred Stock
Dividends payable	$ 13
Liquidation value (in dollars per share)	$ 1,217
Preferred stock, shares outstanding	325,000
Minimum | Common Stock
Series A Preferred Stock
Additional shares of common stock to be issued upon conversion	5,215,718
Maximum | Common Stock
Series A Preferred Stock
Additional shares of common stock to be issued upon conversion	6,401,108
Eagle Property Acquisition
Series A Preferred Stock
Preferred stock, shares designated		325,000
Liquidation value (in dollars per share)		$ 1,000
Rate of interest for preferred stock (as a percent)	8.00%
Conversion rate for preferred stock (in dollars per share)	$ 13.50
Period required to convert preferred stock into common stock	15 days
Eagle Property Acquisition | Minimum
Series A Preferred Stock
Conversion rate for preferred stock (in dollars per share)	$ 11.00
Eagle Property Acquisition | Maximum
Series A Preferred Stock
Conversion rate for preferred stock (in dollars per share)	$ 13.50
$13.50
Series A Preferred Stock
Number of Common Shares Issuable Upon Conversion	29,289,792
$11.00
Series A Preferred Stock
Number of Common Shares Issuable Upon Conversion	35,946,563