Earnings per Share - Composition of Weighted-Average Common Shares (Denominator) Used in Basic and Diluted Earnings Per Share (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share [Abstract]
Weighted Average Number of Shares Issued, Basic	105,563,455	105,563,455	105,563,455	105,563,455
Average treasury shares (in shares)	(7,823,276)	(410,247)	(6,968,649)	(476,286)
Averaged unearned ESOP shares (in shares)	0	(50,170)	0	(67,580)
Weighted Average Number of Shares, Restricted Stock	(175,480)	(208,777)	(172,850)	(167,095)
Weighted average common shares and common stock equivalents used to calculate basic earnings per share (in shares)	97,564,699	104,894,261	98,421,956	104,852,494
Additional common stock equivalents (nonvested stock) used to calculate diluted earnings per share	12,311	6,978	7,267	3,049
Weighted average common shares and common stock equivalents used to calculate diluted earnings per share (in shares)	97,577,010	104,901,239	98,429,223	104,855,543