FAIR VALUE OF FINANCIAL INSTRUMENTS (Fair Value By Balance Sheet Location) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Assets:
Securities—trading	$ 30,889	$ 34,134
Securities—available-for-sale	1,006,414	1,138,573
Securities—held-to-maturity	283,303	226,627
Liabilities:
FHLB advances at fair value	62,342	133,381
Carrying Value
Assets:
Cash and cash equivalents	245,917	261,917
Securities—trading	30,889	34,134
Securities—available-for-sale	1,006,414	1,138,573
Securities—held-to-maturity	271,975	220,666
Loans receivable held for sale	123,144	44,712
Loans receivable	7,398,637	7,314,504
FHLB stock	12,826	16,057
Bank-owned life insurance	158,831	156,865
Mortgage servicing rights	14,826	13,295
Liabilities:
Demand, interest checking and money market accounts	5,601,838	5,416,556
Regular savings	1,387,123	1,284,642
Certificates of deposit	1,123,011	1,353,870
FHLB advances at fair value	62,342	133,381
Other borrowings	108,911	98,325
Junior subordinated debentures at fair value	94,364	92,480
Estimated Fair Value
Assets:
Cash and cash equivalents	245,917	261,917
Securities—trading	30,889	34,134
Securities—available-for-sale	1,006,414	1,138,573
Securities—held-to-maturity	283,303	226,627
Loans receivable held for sale	124,749	45,600
Loans receivable	7,334,303	7,084,631
FHLB stock	12,826	16,057
Bank-owned life insurance	158,831	156,865
Mortgage servicing rights	15,170	17,370
Liabilities:
Demand, interest checking and money market accounts	5,601,838	5,416,556
Regular savings	1,387,123	1,284,642
Certificates of deposit	1,109,322	1,332,825
FHLB advances at fair value	62,342	133,381
Other borrowings	108,911	98,325
Junior subordinated debentures at fair value	94,364	92,480
Interest rate swaps [Member] | Carrying Value
Assets:
Derivatives:	18,999	11,984
Liabilities:
Derivatives:	18,999	11,984
Interest rate swaps [Member] | Estimated Fair Value
Assets:
Derivatives:	18,999	11,984
Liabilities:
Derivatives:	18,999	11,984
Interest Rate Forward Sales Commitments [Member] | Carrying Value
Assets:
Derivatives:	1,119	471
Liabilities:
Derivatives:	540	50
Interest Rate Forward Sales Commitments [Member] | Estimated Fair Value
Assets:
Derivatives:	1,119	471
Liabilities:
Derivatives:	$ 540	$ 50