Earnings Per Common Share - Calculation of Both Basic and Diluted Earnings Per Common Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Net income	$ 27,682	$ 27,121	$ 91,037	$ 92,353
Basic weighted average number of common shares outstanding		199,445,874
Diluted weighted average number of common shares outstanding	200,614,091	199,445,874	200,406,801	199,206,945
Earnings per common share:
Basic	$ 0.14	$ 0.14	$ 0.45	$ 0.46
Diluted	$ 0.14	$ 0.14	$ 0.45	$ 0.46