Stockholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2015 |
Dec. 31, 2014 |
|
| Subsidiary, Sale of Stock [Line Items] | ||
| Common stock, shares issued (in shares) | 418,401,109 | 411,350,440 |
| Weighted Average | ||
| Subsidiary, Sale of Stock [Line Items] | ||
| Price per share (in USD per share) | $ 12.07 | |
| ATM Program | ||
| Subsidiary, Sale of Stock [Line Items] | ||
| Common stock, shares issued (in shares) | 6,600,000 | |
| Proceeds from issuance of common stock | $ 79.8 | |
| Net proceeds from common stock offering | $ 78.6 |