STOCKHOLDERS' EQUITY AND EARNINGS PER SHARE (Details 5) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Unrealized (losses) gains on available-for-sale investment securities:
Net unrealized (losses) gains arising during the period, before-tax amount		$ (8,473)	$ 25,681	$ 12,009	$ 52,271
Reclassification adjustment for gains included in net income, before-tax amount	[1]	(5,554)	(671)	(9,958)	(4,089)
Net change, before-tax amount		(14,027)	25,010	2,051	48,182
Unrealized gains (losses) on other investments:
Net unrealized gains (losses) arising during the period, before-tax amount		18	(7)	5	(36)
Net change, before-tax amount		18	(7)	5	(36)
Other comprehensive (loss) income, before-tax amount		(14,009)	25,003	2,056	48,146
Unrealized (losses) gains on available-for-sale investment securities:
Net unrealized (losses) gains arising during the period, tax expense or benefit		3,559	(10,786)	(5,043)	(21,954)
Reclassification adjustment for gains included in net income, tax expense or benefit		2,333	282	4,182	1,717
Net change, tax expense or benefit		5,892	(10,504)	(861)	(20,237)
Unrealized gains (losses) on other investments:
Net unrealized gains (losses) arising during the period, tax expense or benefit		(8)	3	(2)	15
Net change, tax expense or benefit		(8)	3	(2)	15
Other comprehensive (loss) income, tax expense or benefit		5,884	(10,501)	(863)	(20,222)
Unrealized (losses) gains on available-for-sale investment securities:
Net unrealized (losses) gains arising during the period, net-of-tax amount		(4,914)	14,895	6,966	30,317
Reclassification adjustment for gains included in net income, net-of-tax amount		(3,221)	(389)	(5,776)	(2,372)
Net change, net-of-tax amount		(8,135)	14,506	1,190	27,945
Unrealized gains (losses) on other investments:
Net unrealized gains (losses) arising during the period, net-of-tax amount		10	(4)	3	(21)
Net change, net-of-tax amount		10	(4)	3	(21)
Other comprehensive (loss) income		$ (8,125)	$ 14,502	$ 1,193	$ 27,924

[1] The pretax amount is reported in net gains on sales of available-for-sale investment securities in the consolidated statements of income.