Equity Offering (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	6 Months Ended
	Mar. 05, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Class of Stock [Line Items]
Proceeds from issuance of common stock, net of offering costs			$ 754,163	$ 0
Common Stock
Class of Stock [Line Items]
Equity issuance, net of offering costs (in shares)	69,000,000	0		0
Share price (dollars per share)	$ 11.05
Proceeds from issuance of common stock, net of offering costs	$ 754,200
Common Stock | Warburg Pincus LLC
Class of Stock [Line Items]
Equity issuance, net of offering costs (in shares)	29,800,000
Ownership percentage held by largest equity investor (percentage)	41.00%