Other Income and Other Expense - Other Income and Other Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other income:
Credit-related fee income	$ 70,424	$ 81,558	$ 72,454
Letter of credit fees		52,724	56,708
Bank owned life insurance		52,984	50,004
Other expense:
Professional services	268,060	267,540	324,460
Amortization of capitalized servicing rights	$ 50,982	$ 49,906	$ 68,410