Other Non-Interest Income and Expense (Other Non-Interest Income and Expense) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Income and Expenses [Abstract]
Other	$ 37,222	$ 41,144	$ 35,656
Total other non-interest income	37,222	41,144	35,656
Advertising, promotions and public relations	29,337	27,677	28,858
Professional services	27,968	26,664	26,283
Travel/meals and entertainment	15,066	14,393	15,346
Check card expense	12,479	15,572	13,008
Other	90,439	94,682	82,066
Total other non-interest expense	$ 175,289	$ 178,988	$ 165,561