Schedule of Reconciliation of Numerator and Denominator of Earnings Per Common Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Earnings Per Share [Abstract]
Net income	$ 18,206		$ 5,472
Weighted average common shares outstanding	78,375,335		72,736,107
Weighted average potential dilutive common shares	860,860	[1]	4,143,156	[1]
Weighted average common shares outstanding - assuming dilution	79,236,195		76,879,263
Net income per common share - basic	$ 0.23		$ 0.08
Net income per common share - diluted	$ 0.23		$ 0.07

[1] Potential common shares consist of common stock issuable under the assumed exercise of stock options and restricted stock awards using the treasury stock method. For the period ended March 31, 2014, a total of 535,484 options to purchase shares of common stock were excluded from the computation as they were anti-dilutive.