INVESTMENTS (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Available-for-sale
Cost or Amortized Cost	$ 1,380,774	$ 1,294,350
Gross Unrealized Gains	42,830	84,615
Gross Unrealized Losses	(24,094)	(383)
Fair Value	1,399,510	1,378,582
Held-to-maturity
Amortized Cost/Carrying Value	651	11,728
Gross Unrecognized Gains	50	140
Fair Value	701	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	8,561	11,609
Gross Unrealized Gains	80	150
Gross Unrealized Losses	(53)
Fair Value	8,588	11,759
Held-to-maturity
Amortized Cost/Carrying Value		10,076
Gross Unrecognized Gains		74
Fair Value		10,150
Corporate
Available-for-sale
Cost or Amortized Cost	493,568	535,437
Gross Unrealized Gains	23,612	45,497
Gross Unrealized Losses	(7,429)	(226)
Fair Value	509,751	580,708
Mortgage-backed
Available-for-sale
Cost or Amortized Cost	257,996	234,629
Gross Unrealized Gains	8,640	15,758
Gross Unrealized Losses	(3,181)
Fair Value	263,455	250,387
ABS/CMBS
Available-for-sale
Cost or Amortized Cost	94,050	72,681
Gross Unrealized Gains	1,561	4,648
Gross Unrealized Losses	(2,190)
Fair Value	93,421	77,329
Non-U.S. govt. & agency
Available-for-sale
Cost or Amortized Cost	8,412	8,410
Gross Unrealized Gains	437	957
Fair Value	8,849	9,367
U.S. government
Available-for-sale
Cost or Amortized Cost	16,994	16,358
Gross Unrealized Gains	263	355
Gross Unrealized Losses	(2)
Fair Value	17,255	16,713
Municipal
Available-for-sale
Cost or Amortized Cost	501,193	415,226
Gross Unrealized Gains	8,237	17,250
Gross Unrealized Losses	(11,239)	(157)
Fair Value	498,191	432,319
Held-to-maturity
Amortized Cost/Carrying Value	651	1,652
Gross Unrecognized Gains	50	66
Fair Value	701	1,718
Equity securities
Available-for-sale
Cost or Amortized Cost	240,066	240,287
Gross Unrealized Gains	177,104	136,376
Gross Unrealized Losses	(356)	(875)
Fair Value	$ 416,814	$ 375,788

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