Parent Company Financial Statements - Condensed Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments in consolidated subsidiaries
Total assets	$ 155,107,160	$ 142,601,105
Liabilities
Long-term borrowings	3,485,369	4,382,193
Total liabilities	137,203,755	126,413,822
Shareholders’ equity	17,903,405	16,187,283	$ 15,716,649	$ 15,460,191
Total liabilities and shareholders’ equity	155,107,160	142,601,105
Parent Company [Member]
Assets
Cash in subsidiary bank	92,836	100,593
Due from consolidated bank subsidiaries
Money-market savings	1,335,857	699,476
Current income tax receivable	754
Total due from consolidated bank subsidiaries	1,336,611	699,476
Investments in consolidated subsidiaries
Banks	17,533,772	16,554,287
Other	220,496	125,988
Investments in trust preferred entities (note 20)	22,672	22,846
Other assets	98,010	92,170
Total assets	19,304,397	17,595,360
Liabilities
Accrued expenses and other liabilities	103,242	96,664
Long-term borrowings	1,297,750	1,311,413
Total liabilities	1,400,992	1,408,077
Shareholders’ equity	17,903,405	16,187,283
Total liabilities and shareholders’ equity	$ 19,304,397	$ 17,595,360