BUSINESS SEGMENTS (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Segment Reporting Information
Interest income	$ 276,172	$ 263,261
Charge for funds used	(88,280)	(70,094)
Interest spread on funds used	187,892	193,167
Interest expense	(23,968)	(27,544)
Credit on funds provided	88,280	70,094
Interest spread on funds provided	64,312	42,550
Net interest income before provision for credit losses	252,204	235,717
(Reversal of) provision for credit losses	1,440	4,987
Depreciation, amortization and (accretion), net	12,758	4,127
Segment pretax profit	144,671	146,826
Segment assets	33,109,169	29,906,835	$ 32,350,922
Operating Segments | Retail Banking
Segment Reporting Information
Interest income	77,371	87,446
Charge for funds used	(22,652)	(23,298)
Interest spread on funds used	54,719	64,148
Interest expense	(14,606)	(12,224)
Credit on funds provided	72,431	57,668
Interest spread on funds provided	57,825	45,444
Net interest income before provision for credit losses	112,544	109,592
(Reversal of) provision for credit losses	(1,582)	731
Depreciation, amortization and (accretion), net	43	1,682
Segment pretax profit	45,945	52,935
Segment assets	7,203,470	7,540,501
Operating Segments | Commercial Banking
Segment Reporting Information
Interest income	177,082	158,786
Charge for funds used	(53,791)	(37,351)
Interest spread on funds used	123,291	121,435
Interest expense	(4,026)	(4,263)
Credit on funds provided	9,977	8,016
Interest spread on funds provided	5,951	3,753
Net interest income before provision for credit losses	129,242	125,188
(Reversal of) provision for credit losses	3,022	4,256
Depreciation, amortization and (accretion), net	(10,773)	(10,477)
Segment pretax profit	92,829	93,175
Segment assets	17,939,537	15,491,368
Operating Segments | Other
Segment Reporting Information
Interest income	21,719	17,029
Charge for funds used	(11,837)	(9,445)
Interest spread on funds used	9,882	7,584
Interest expense	(5,336)	(11,057)
Credit on funds provided	5,872	4,410
Interest spread on funds provided	536	(6,647)
Net interest income before provision for credit losses	10,418	937
(Reversal of) provision for credit losses	0	0
Depreciation, amortization and (accretion), net	23,488	12,922
Segment pretax profit	5,897	716
Segment assets	$ 7,966,162	$ 6,874,966