Reconciliation of Components Used to Derive Basic and Diluted EPS (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share [Line Items]
Net Income	$ 13,279	$ 4,203	$ 76,395	$ 22,641
Weighted-Average Shares, Basic	31,475,976	18,888,474	31,474,042	18,886,415
Weighted-Average Shares, Effect of Dilutive Securities - Options, Warrants and Unvested Restricted Stock	69,135	18,825	32,725	19,428
Weighted-Average Shares, Diluted	31,545,111	18,907,299	31,506,767	18,905,843
Per Share Amount, Basic	$ 0.42	$ 0.22	$ 2.43	$ 1.20
Per Share Amount, Effect of Dilutive Securities Options, Warrants and Unvested Restricted Stock			$ (0.01)
Per Share Amount, Diluted	$ 0.42	$ 0.22	$ 2.42	$ 1.20