MORTGAGE SERVICING RIGHTS (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Data and assumptions used in fair value calculation [Abstract]
Unpaid principal balance	$ 5,649,897,000	$ 5,543,619,000	$ 5,649,897,000	$ 5,543,619,000	$ 5,577,325,000
Weighted-average prepayment speed (CPR)	10.60%	11.40%			10.30%
Discount rate (annual percentage) (in hundredths)	9.80%	10.30%			10.30%
Weighted-average coupon interest rate (percentage) (in hundredths)	4.10%	4.20%			4.20%
Weighted-average remaining maturity (months)	313 months	308 months			310 months
Weighted-average servicing fee (basis points)	0.265%	0.267%			0.266%
Activity in mortgage servicing asset [Roll Forward]
Fair value as of beginning of period			54,662,000	37,882,000	37,882,000
Additions [Abstract]
Origination of servicing assets			6,425,000	12,106,000
Changes in fair value [Abstract]
Due to payoffs/paydowns			(4,313,000)	(5,004,000)
Due to change in valuation inputs or assumptions used in the valuation model			(3,010,000)	6,049,000
Other changes in fair value			(5,000)	(8,000)
Fair value as of end of period	53,759,000	51,025,000	53,759,000	51,025,000	54,662,000
Contractually specified servicing fees, late fees, and ancillary fees [Abstract]
Contractual servicing fees	3,800,000	3,700,000	11,300,000	10,800,000
Late and other ancillary fees	$ 293,000	$ 335,000	$ 933,000	$ 1,000,000