SUMMARY OF QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Consolidated quarterly financial data
Interest income	$ 32,039	$ 34,009	$ 34,119	$ 34,401	$ 35,930	$ 34,128	$ 33,814	$ 79,587	$ 134,568	$ 183,459	$ 195,115
Interest Expense	5,300	5,470	5,352	5,271	5,379	5,556	5,502	6,367	21,393	22,804	30,255
NET INTEREST INCOME	26,739	28,539	28,767	29,130	30,551	28,572	28,312	73,220	113,175	160,655	164,860
Provision for loan losses	503	2,200	905	(625)	1,324	2,083	466	11,170	2,983	15,043	17,966
NET INTEREST INCOME AFTER PROVISION FOR LOAN LOSSES	26,236	26,339	27,862	29,755	29,227	26,489	27,846	62,050	110,192	145,612	146,894
Non interest income	7,122	7,539	10,783	22,525	9,338	34,845	14,086	106,809	47,969	165,078	119,624
Non interest expenses	30,337	26,325	29,699	31,302	28,379	29,762	27,451	41,153	117,663	126,745	122,321
INCOME BEFORE INCOME TAX EXPENSE	3,021	7,553	8,946	20,978	10,186	31,572	14,481	127,706	40,498	183,945	144,197
Income tax expense	1,676	2,950	2,827	7,622	3,565	10,904	4,903	45,234	15,075	64,606	50,048
NET INCOME	$ 1,345	$ 4,603	$ 6,119	$ 13,356	$ 6,621	$ 20,668	$ 9,578	$ 82,472	$ 25,423	$ 119,339	$ 94,149
Class A Common Stock
Basic earnings per share:
Basic earnings per share (in dollars per share)	$ 0.07	$ 0.22	$ 0.30	$ 0.64	$ 0.33	$ 0.99	$ 0.46	$ 3.94	$ 1.23	$ 5.71	$ 4.50
Diluted earnings per share:
Diluted earnings per share (in dollars per share)	$ 0.07	$ 0.22	$ 0.30	$ 0.64	$ 0.33	$ 0.98	$ 0.46	$ 3.92	$ 1.22	$ 5.69	$ 4.49
Dividends declared per common share:
Dividend declared common stock, per share (in dollars per share)	$ 0.176	$ 0.176	$ 0.176	$ 0.165	$ 1.265	$ 0.165	$ 0.165	$ 0.154	$ 0.693	$ 1.749	$ 0.605
Class B Common Stock
Basic earnings per share:
Basic earnings per share (in dollars per share)	$ 0.05	$ 0.21	$ 0.28	$ 0.63	$ 0.21	$ 0.97	$ 0.44	$ 3.92	$ 1.17	$ 5.55	$ 4.45
Diluted earnings per share:
Diluted earnings per share (in dollars per share)	$ 0.05	$ 0.21	$ 0.28	$ 0.62	$ 0.21	$ 0.97	$ 0.44	$ 3.90	$ 1.16	$ 5.53	$ 4.44
Dividends declared per common share:
Dividend declared common stock, per share (in dollars per share)	$ 0.160	$ 0.160	$ 0.160	$ 0.150	$ 0.150	$ 0.150	$ 0.150	$ 0.140	$ 0.630	$ 1.590	$ 0.550