Condensed Statements of Condition (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
ASSETS:
Cash and cash equivalents	$ 741,870	$ 1,474,955	$ 2,528,169	$ 557,850
Other assets	436,460	358,941
Total assets	53,640,821	51,899,376
LIABILITIES AND STOCKHOLDERS' EQUITY:
Junior subordinated debentures	359,866	359,508
Other liabilities	428,411	271,845
Total liabilities	46,929,127	45,244,141
Stockholders' equity	6,711,694	6,655,235	6,795,376	6,123,991
Total liabilities and stockholders' equity	53,640,821	51,899,376
Parent Company
ASSETS:
Cash and cash equivalents	183,063	228,618	$ 90,536	$ 63,727
Investments in subsidiaries	7,169,066	7,064,341
Receivables from subsidiaries	2,249	6,455
Other assets	23,338	23,724
Total assets	7,377,716	7,323,138
LIABILITIES AND STOCKHOLDERS' EQUITY:
Junior subordinated debentures	359,866	359,508
Subordinated notes	295,066	294,697
Other liabilities	11,090	13,698
Total liabilities	666,022	667,903
Stockholders' equity	6,711,694	6,655,235
Total liabilities and stockholders' equity	$ 7,377,716	$ 7,323,138