INVESTMENTS (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Available-for-sale
Cost or Amortized Cost	$ 1,339,224	$ 1,294,350
Gross Unrealized Gains	75,621	84,615
Gross Unrealized Losses	(1,275)	(383)
Fair Value	1,413,570	1,378,582
Held-to-maturity
Amortized Cost/Carrying Value	5,736	11,728
Gross Unrecognized Gains	70	140
Gross Unrecognized Losses	0
Fair Value	5,806	11,868
Fair value measured on recurring basis \| Significant Unobservable Inputs (Level 3)
INVESTMENTS
Total assets at fair value	0
U.S. agency
Available-for-sale
Cost or Amortized Cost	11,585	11,609
Gross Unrealized Gains	118	150
Fair Value	11,703	11,759
Held-to-maturity
Amortized Cost/Carrying Value	5,085	10,076
Gross Unrecognized Gains	10	74
Fair Value	5,095	10,150
Corporate
Available-for-sale
Cost or Amortized Cost	538,511	535,437
Gross Unrealized Gains	42,304	45,497
Gross Unrealized Losses	(632)	(226)
Fair Value	580,183	580,708
Mortgage-backed
Available-for-sale
Cost or Amortized Cost	251,591	234,629
Gross Unrealized Gains	13,359	15,758
Gross Unrealized Losses	(177)
Fair Value	264,773	250,387
ABS/CMO
Available-for-sale
Cost or Amortized Cost	84,226	72,681
Gross Unrealized Gains	3,743	4,648
Gross Unrealized Losses	(193)
Fair Value	87,776	77,329
Non-U.S. govt. & agency
Available-for-sale
Cost or Amortized Cost	8,411	8,410
Gross Unrealized Gains	833	957
Fair Value	9,244	9,367
U.S. government
Available-for-sale
Cost or Amortized Cost	16,997	16,358
Gross Unrealized Gains	330	355
Fair Value	17,327	16,713
Municipal
Available-for-sale
Cost or Amortized Cost	427,903	415,226
Gross Unrealized Gains	14,934	17,250
Gross Unrealized Losses	(273)	(157)
Fair Value	442,564	432,319
Held-to-maturity
Amortized Cost/Carrying Value	651	1,652
Gross Unrecognized Gains	60	66
Fair Value	711	1,718
Equity securities
Available-for-sale
Cost or Amortized Cost	235,195	240,287
Gross Unrealized Gains	172,775	136,376
Gross Unrealized Losses	(290)	(875)
Fair Value	$ 407,680	$ 375,788

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