Parent Company Financial Statements - Condensed Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments in consolidated subsidiaries
Total assets	$ 118,593,487	$ 123,449,206
Liabilities
Long-term borrowings	8,141,430	9,493,835
Total liabilities	102,342,668	106,962,584
Shareholders’ equity	16,250,819	16,486,622	$ 16,173,289	$ 12,335,896
Total liabilities and shareholders’ equity	118,593,487	123,449,206
Parent Company [Member]
Assets
Cash in subsidiary bank	13,379	15,003
Due from consolidated bank subsidiaries
Money-market savings	1,616,147	1,767,184
Current income tax receivable	4,437	3,061
Total due from consolidated bank subsidiaries	1,620,584	1,770,245
Investments in consolidated subsidiaries
Banks	14,841,794	15,003,964
Other	253,904	161,201
Investments in unconsolidated subsidiaries (note 19)	23,453	23,643
Investment in Bayview Lending Group LLC		11,908
Other assets	66,023	71,687
Total assets	16,819,137	17,057,651
Liabilities
Accrued expenses and other liabilities	49,093	54,487
Long-term borrowings	519,225	516,542
Total liabilities	568,318	571,029
Shareholders’ equity	16,250,819	16,486,622
Total liabilities and shareholders’ equity	$ 16,819,137	$ 17,057,651