Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net Income									$ 93,641	$ 385,721	$ 39,133
Weighted average shares outstanding - basic (in shares)	62,319,497	62,309,270	62,289,437	62,242,183	62,159,683	62,139,833	62,112,936	62,078,404	62,290,361	62,122,862	61,955,659
Dilutive securities outstanding (in shares)									1,081,402	649,217	275,549
Weighted average shares outstanding - diluted (in shares)	63,613,271	63,461,018	63,107,913	63,004,784	62,867,030	62,845,864	62,610,054	62,682,987	63,371,763	62,772,079	62,231,208
Earnings per share - basic (in dollars per share)	$ 0.36	$ 0.34	$ 0.45	$ 0.36	$ 0.34	$ 0.49	$ 5.17	$ 0.21	$ 1.50	$ 6.21	$ 0.63
Earnings per share - diluted (in dollars per share)	$ 0.35	$ 0.33	$ 0.44	$ 0.36	$ 0.33	$ 0.49	$ 5.13	$ 0.21	$ 1.48	$ 6.14	$ 0.63
Weighted Average antidilutive securities outstanding (in shares)									66,106	14,022	21,239
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	2,902,566				2,749,044				2,902,566	2,749,044
Class of Warrant or Right, Exercise Price of Warrants or Rights	13.13				13.86				13.13	13.86
Stock options
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted Average antidilutive securities outstanding (in shares)									64,797	13,792	16,511
Restricted shares
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted Average antidilutive securities outstanding (in shares)									1,309	230	4,728