SEGMENT INFORMATION (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting Information
Interest income	$ 287,135	$ 285,948	$ 294,442	$ 286,173	$ 293,203	$ 281,706	$ 255,353	$ 238,423	$ 1,153,698		$ 1,068,685		$ 1,051,095
Charge for funds used									(283,384)		(220,957)		(160,092)
Interest spread on funds used									870,314		847,728		891,003
Interest expense	(27,647)	(28,974)	(27,992)	(28,207)	(28,195)	(27,456)	(27,709)	(29,132)	(112,820)		(112,492)		(132,168)
Credit on funds provided									283,384		220,957		160,092
Interest spread on funds provided									170,564		108,465		27,924
Net interest income (loss)	259,488	256,974	266,450	257,966	265,008	254,250	227,644	209,291	1,040,878		956,193		918,927
Provision for loan losses									49,158		22,364		65,184
Depreciation, amortization and accretion									114,121	[1]	97,110	[1]	43,751	[1]
Goodwill	469,433				337,438				469,433		337,438		337,438
Segment pre-tax profit	113,047	75,112	115,606	111,690	98,564	108,906	111,870	106,510	415,455		425,850		425,592
Segment assets	28,738,049				24,730,068				28,738,049		24,730,068		22,536,110
Retail Banking
Segment Reporting Information
Interest income									378,445		374,818		356,244
Charge for funds used									(94,162)		(86,552)		(85,811)
Interest spread on funds used									284,283		288,266		270,433
Interest expense									(48,020)		(47,287)		(57,401)
Credit on funds provided									225,873		173,194		130,713
Interest spread on funds provided									177,853		125,907		73,312
Net interest income (loss)									462,136		414,173		343,745
Provision for loan losses									14,979		10,911		28,729
Depreciation, amortization and accretion									14,376	[1]	19,865	[1]	12,869	[1]
Goodwill	357,207				320,566				357,207		320,566		320,566
Segment pre-tax profit									166,637		123,876		74,836
Segment assets	7,621,808				7,820,191				7,621,808		7,820,191		6,552,217
Commercial Banking
Segment Reporting Information
Interest income									715,075		627,118		617,041
Charge for funds used									(141,652)		(116,161)		(118,688)
Interest spread on funds used									573,423		510,957		498,353
Interest expense									(15,650)		(15,185)		(23,226)
Credit on funds provided									38,592		29,262		13,138
Interest spread on funds provided									22,942		14,077		(10,088)
Net interest income (loss)									596,365		525,034		488,265
Provision for loan losses									34,179		11,453		36,455
Depreciation, amortization and accretion									(8,372)	[1]	8,120	[1]	(13,277)	[1]
Goodwill	112,226				16,872				112,226		16,872		16,872
Segment pre-tax profit									276,601		272,369		266,168
Segment assets	15,595,862				11,545,405				15,595,862		11,545,405		10,421,160
Other
Segment Reporting Information
Interest income									60,178		66,749		77,810
Charge for funds used									(47,570)		(18,244)		44,407
Interest spread on funds used									12,608		48,505		122,217
Interest expense									(49,150)		(50,020)		(51,541)
Credit on funds provided									18,919		18,501		16,241
Interest spread on funds provided									(30,231)		(31,519)		(35,300)
Net interest income (loss)									(17,623)		16,986		86,917
Depreciation, amortization and accretion									108,117	[1]	69,125	[1]	44,159	[1]
Segment pre-tax profit									(27,783)		29,605		84,588
Segment assets	$ 5,520,379				$ 5,364,472				$ 5,520,379		$ 5,364,472		$ 5,562,733

[1] Includes amortization and accretion related to the FDIC indemnification asset.