Income Taxes (Income Tax Computed by Applying U.S. Federal Statutory Income Tax Rate) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Income tax expense computed at the statutory rate	$ 101,808	$ 107,966	$ 100,182
Effect of tax-exempt interest	(46,535)	(36,543)	(35,741)
Bank owned life insurance income	(1,086)	(1,413)	(1,416)
Accrual adjustment for premium amortization on municipal securities	0	0	4,146
Other	(1,172)	513	1,529
Income tax expense, as reported	$ 53,015	$ 70,523	$ 68,700