Income Per Common Share - Summary of Basic and Diluted (Loss) Income Per Common Share (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
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Basic weighted average number of shares outstanding (in shares)									36,546,227	31,753,110	24,736,841
Effect of dilutive securities:
Diluted average shares outstanding (in shares)									38,767,556	33,236,343	25,796,197
Net (loss) income available to common stockholders	$ 26,295	$ 12,082	$ 12,277	$ 6,682	$ 18,005	$ 5,638	$ 12,285	$ 8,697	$ 57,336	$ 44,625	$ 127,604
Net income available to common stockholders	$ 27,128	$ 12,277	$ 13,250	$ 7,606	$ 20,810	$ 7,622	$ 14,752	$ 11,342	$ 60,261	$ 54,526	$ 135,603
Basic income per common share (in USD per share)	$ 0.72	$ 0.33	$ 0.34	$ 0.18	$ 0.54	$ 0.18	$ 0.39	$ 0.28	$ 1.57	$ 1.41	$ 5.16
Diluted income per common share (in USD per share)	$ 0.68	$ 0.31	$ 0.32	$ 0.18	$ 0.52	$ 0.17	$ 0.38	$ 0.27	$ 1.48	$ 1.34	$ 4.95
Potentially antidilutive securities not included in the calculation of diluted income per common share (weighted average):
Number of equity units	5,113,475								5,113,475
Unvested stock options
Potentially antidilutive securities not included in the calculation of diluted income per common share (weighted average):
Potentially antidilutive securities note included in the calculation of diluted loss per common share									180,000
Preferred shares, stock options, and warrants
Effect of dilutive securities:
Dilutive securities (in shares)									1,326,399	1,424,272	1,059,356
Tangible Equity Units
Effect of dilutive securities:
Dilutive securities (in shares)									894,930	58,961	0