BUSINESS SEGMENTS (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Segment Reporting Information
Interest income	$ 280,317	$ 264,632	$ 835,354	$ 783,338
Charge for funds used	(81,440)	(82,727)	(252,969)	(226,230)
Interest spread on funds used	198,877	181,905	582,385	557,108
Interest expense	(26,169)	(24,343)	(75,418)	(79,840)
Credit on funds provided	81,440	82,727	252,969	226,230
Interest spread on funds provided	55,271	58,384	177,551	146,390
Net interest income before provision for credit losses	254,148	240,289	759,936	703,498
(Reversal of) provision for credit losses	9,525	7,736	17,018	16,217
Depreciation, amortization and (accretion), net	35,448	7,096	60,680	17,341
Goodwill	469,433	469,433	469,433	469,433	$ 469,433
Segment pretax profit (loss)	123,464	138,989	411,051	430,236
Segment assets	33,255,275	31,119,676	33,255,275	31,119,676	$ 32,350,922
Retail Banking
Segment Reporting Information
Interest income	77,186	81,911	233,192	252,085
Charge for funds used	(24,320)	(20,795)	(70,770)	(65,452)
Interest spread on funds used	52,866	61,116	162,422	186,633
Interest expense	(14,855)	(13,727)	(44,133)	(38,946)
Credit on funds provided	68,622	68,783	210,831	187,401
Interest spread on funds provided	53,767	55,056	166,698	148,455
Net interest income before provision for credit losses	106,633	116,172	329,120	335,088
(Reversal of) provision for credit losses	(3,709)	1,455	(2,846)	(1,268)
Depreciation, amortization and (accretion), net	782	1,827	279	6,743
Goodwill	357,207	357,207	357,207	357,207
Segment pretax profit (loss)	32,304	52,325	114,513	160,609
Segment assets	7,606,611	7,274,494	7,606,611	7,274,494
Commercial Banking
Segment Reporting Information
Interest income	180,095	166,693	534,603	482,816
Charge for funds used	(53,262)	(41,447)	(159,734)	(117,125)
Interest spread on funds used	126,833	125,246	374,869	365,691
Interest expense	(3,699)	(4,765)	(11,965)	(13,738)
Credit on funds provided	8,206	8,849	26,655	24,859
Interest spread on funds provided	4,507	4,084	14,690	11,121
Net interest income before provision for credit losses	131,340	129,330	389,559	376,812
(Reversal of) provision for credit losses	13,234	6,281	19,864	17,485
Depreciation, amortization and (accretion), net	(5,875)	(13,496)	(25,915)	(30,027)
Goodwill	112,226	112,226	112,226	112,226
Segment pretax profit (loss)	80,393	96,605	268,401	287,049
Segment assets	18,549,562	17,125,065	18,549,562	17,125,065
Other
Segment Reporting Information
Interest income	23,036	16,028	67,559	48,437
Charge for funds used	(3,858)	(20,485)	(22,465)	(43,653)
Interest spread on funds used	19,178	(4,457)	45,094	4,784
Interest expense	(7,615)	(5,851)	(19,320)	(27,156)
Credit on funds provided	4,612	5,095	15,483	13,970
Interest spread on funds provided	(3,003)	(756)	(3,837)	(13,186)
Net interest income before provision for credit losses	16,175	(5,213)	41,257	(8,402)
(Reversal of) provision for credit losses	0	0	0	0
Depreciation, amortization and (accretion), net	40,541	18,765	86,316	40,625
Goodwill	0	0	0	0
Segment pretax profit (loss)	10,767	(9,941)	28,137	(17,422)
Segment assets	$ 7,099,102	$ 6,720,117	$ 7,099,102	$ 6,720,117