Earnings per Share (Schedule of Earnings per Share, Basic and Diluted, by Common Class, Including Two Class Method) (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]                      
Net income (loss) attributable to common stockholders $ (161,143) $ (191,819) $ (118,014) $ (3,004) $ 26,671 $ 9,807 $ 2,016 $ (1,965) $ (473,980) $ 36,529 $ 39,964
Weighted average common shares outstanding basic (shares) 77,685,049 77,628,120 77,611,167 77,114,826 75,994,979 60,006,903 58,702,982 58,204,532 77,511,677 63,270,733 60,220,115
Incremental shares from unvested restricted shares                 0 2,451,903 2,869,490
Incremental shares from outstanding stock options                 0 97,491 26,095
Incremental shares from outstanding PBUs                 0 672,462 502,701
Weighted average common shares outstanding diluted (shares) 77,685,049 77,628,120 77,611,167 77,114,826 78,577,762 63,399,446 61,922,874 58,204,532 77,511,677 66,492,589 63,618,401
Basic (dollars per share) $ (2.07) $ (2.47) $ (1.52) $ (0.04) $ 0.35 $ 0.16 $ 0.03 $ (0.03) $ (6.11) $ 0.58 $ 0.66
Diluted (dollars per share) $ (2.07) $ (2.47) $ (1.52) $ (0.04) $ 0.34 $ 0.15 $ 0.03 $ (0.03) $ (6.11) $ 0.55 $ 0.63
Common shares excluded from denominator as anti-dilutive (shares)                 195,252 34,058 3,505
Unvested restricted shares                      
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]                      
Common shares excluded from denominator as anti-dilutive (shares)                 177,663 34,058 3,505
Unvested PBUs                      
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]                      
Common shares excluded from denominator as anti-dilutive (shares)                 17,589 0 0