BUSINESS SEGMENTS (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Segment Reporting Information
Interest income	$ 278,865	$ 255,445	$ 555,037	$ 518,706
Charge for funds used	(83,249)	(73,408)	(171,529)	(143,502)
Interest spread on funds used	195,616	182,037	383,508	375,204
Interest expense	(25,281)	(27,953)	(49,249)	(55,497)
Credit on funds provided	83,249	73,408	171,529	143,502
Interest spread on funds provided	57,968	45,455	122,280	88,005
Net interest income before provision for credit losses	253,584	227,492	505,788	463,209
(Reversal of) provision for credit losses	6,053	3,494	7,493	8,481
Depreciation, amortization and (accretion), net	12,474	6,119	25,232	10,246
Goodwill	469,433	469,433	469,433	469,433	$ 469,433
Segment pretax profit (loss)	142,916	144,421	287,587	291,247
Segment assets	32,952,212	30,064,072	32,952,212	30,064,072	$ 32,350,922
Operating Segments | Retail Banking
Segment Reporting Information
Interest income	78,635	82,729	156,006	170,175
Charge for funds used	(23,798)	(21,357)	(46,450)	(44,656)
Interest spread on funds used	54,837	61,372	109,556	125,519
Interest expense	(14,672)	(12,996)	(29,278)	(25,219)
Credit on funds provided	69,778	60,950	142,209	118,618
Interest spread on funds provided	55,106	47,954	112,931	93,399
Net interest income before provision for credit losses	109,943	109,326	222,487	218,918
(Reversal of) provision for credit losses	2,445	(3,454)	863	(2,723)
Depreciation, amortization and (accretion), net	(546)	3,235	(503)	4,917
Goodwill	357,207	357,207	357,207	357,207
Segment pretax profit (loss)	36,264	55,349	82,209	108,284
Segment assets	7,437,534	7,373,641	7,437,534	7,373,641
Operating Segments | Commercial Banking
Segment Reporting Information
Interest income	177,426	157,337	354,508	316,122
Charge for funds used	(52,681)	(38,328)	(106,472)	(75,678)
Interest spread on funds used	124,745	119,009	248,036	240,444
Interest expense	(4,240)	(4,710)	(8,266)	(8,973)
Credit on funds provided	8,472	7,995	18,449	16,010
Interest spread on funds provided	4,232	3,285	10,183	7,037
Net interest income before provision for credit losses	128,977	122,294	258,219	247,481
(Reversal of) provision for credit losses	3,608	6,948	6,630	11,204
Depreciation, amortization and (accretion), net	(9,267)	(6,054)	(20,040)	(16,531)
Goodwill	112,226	112,226	112,226	112,226
Segment pretax profit (loss)	95,179	97,269	188,008	190,444
Segment assets	18,196,664	16,141,368	18,196,664	16,141,368
Operating Segments | Other
Segment Reporting Information
Interest income	22,804	15,379	44,523	32,409
Charge for funds used	(6,770)	(13,723)	(18,607)	(23,168)
Interest spread on funds used	16,034	1,656	25,916	9,241
Interest expense	(6,369)	(10,247)	(11,705)	(21,305)
Credit on funds provided	4,999	4,463	10,871	8,874
Interest spread on funds provided	(1,370)	(5,784)	(834)	(12,431)
Net interest income before provision for credit losses	14,664	(4,128)	25,082	(3,190)
(Reversal of) provision for credit losses	0	0	0	0
Depreciation, amortization and (accretion), net	22,287	8,938	45,775	21,860
Goodwill	0	0	0	0
Segment pretax profit (loss)	11,473	(8,197)	17,370	(7,481)
Segment assets	$ 7,318,014	$ 6,549,063	$ 7,318,014	$ 6,549,063