INVESTMENTS IN QUALIFIED AFFORDABLE HOUSING PARTNERSHIPS, TAX CREDIT AND OTHER INVESTMENTS, NET (Details 2) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Consolidated Balance Sheets:
Investments in qualified affordable housing partnerships, net	[1]	$ 193,978				$ 178,962				$ 193,978		$ 178,962
Deferred Tax Assets, Net		135,871				389,601				135,871		389,601
Retained earnings	[1]	1,872,594				1,604,141				1,872,594		1,604,141
Consolidated Statements of Income:
Noninterest expense — amortization of tax credit and other investments	[1]									36,120		44,092		$ 5,973
Income before income taxes		148,485	$ 138,989	$ 144,421	$ 146,826	122,595	$ 85,299	$ 122,966	$ 116,163	578,721	[1]	447,023	[1]	447,146	[1]
Income taxes expense		56,680	44,892	45,673	46,799	27,093	(6,601)	38,661	41,992	194,044	[1]	101,145	[1]	153,822	[1]
Net income		$ 91,805	$ 94,097	$ 98,748	$ 100,027	$ 95,502	$ 91,900	$ 84,305	$ 74,171	$ 384,677	[1]	$ 345,878	[1]	$ 293,324	[1]
EARNINGS PER SHARE AVAILABLE TO COMMON STOCKHOLDERS
BASIC (in dollars per share)		$ 0.64	$ 0.65	$ 0.69	$ 0.70	$ 0.67	$ 0.64	$ 0.59	$ 0.52	$ 2.67	[1]	$ 2.42	[1]	$ 2.10	[1]
DILUTED (in dollars per share)		$ 0.63	$ 0.65	$ 0.68	$ 0.69	$ 0.66	$ 0.64	$ 0.59	$ 0.52	$ 2.66	[1]	$ 2.41	[1]	$ 2.09	[1]
As Previously Reported
Consolidated Balance Sheets:
Investments in qualified affordable housing partnerships, net						$ 178,652						$ 178,652
Deferred Tax Assets, Net						384,367						384,367
Retained earnings						$ 1,598,598						1,598,598
Consolidated Statements of Income:
Noninterest expense — amortization of tax credit and other investments												75,660		$ 27,268
Income before income taxes												415,455		425,850
Income taxes expense												72,972		130,805
Net income												$ 342,483		$ 295,045
EARNINGS PER SHARE AVAILABLE TO COMMON STOCKHOLDERS
BASIC (in dollars per share)												$ 2.39		$ 2.11
DILUTED (in dollars per share)												$ 2.38		$ 2.10

[1] Prior period was restated to reflect the retrospective application of adopting the new accounting guidance related to the Company’s investments in qualified affordable housing projects Accounting Standards Update (“ASU”) 2014-01. Please see Note 9 — Investments in Qualified Affordable Housing Partnerships, Tax Credit and Other Investments, Net to the Consolidated Financial Statements for additional information.