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, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]
Incremental Common Shares Attributable to Call Options and Warrants	0	0	0	0
Weighted Average Number of Shares Issued, Basic	105,563,455	105,563,455	105,563,455	105,563,455
Average treasury shares (in shares)	(11,584,636)	(7,823,276)	(11,232,622)	(6,968,649)
Average unearned nonvested shares	(184,230)	(175,480)	(163,897)	(172,850)
Weighted average common shares and common stock equivalents used to calculate basic earnings per share (in shares)	93,794,589	97,564,699	94,166,936	98,421,956
Additional common stock equivalents (nonvested stock) used to calculate diluted earnings per share	16,954	12,311	10,895	7,267
Weighted average common shares and common stock equivalents used to calculate diluted earnings per share (in shares)	93,811,543	97,577,010	94,177,831	98,429,223