INVESTMENTS (Details 3) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Amortized cost of available-for-sale debt securities by contractual maturity
Due in one year or less	$ 7,792
Due after one year through five years	106,241
Due after five years through 10 years	565,573
Due after 10 years	190,821
Total amortized cost	1,194,129
Fair value of available-for-sale debt securities by contractual maturity
Due in one year or less	7,892
Due after one year through five years	112,624
Due after five years through 10 years	594,238
Due after 10 years	194,651
Total fair value	1,251,451	1,146,317
Amortized cost of debt securities held-to-maturity by contractual maturity
Due in one year or less	4,984
Due after one year through five years	652
Due after 10 years	156,120
Total amortized cost	161,756
Fair value of debt securities held-to-maturity by contractual maturity
Due in one year or less	5,182
Due after one year through five years	740
Due after 10 years	154,053
Total fair value	159,975
Mtge/ABS/CMO
Amortized cost of available-for-sale debt securities by contractual maturity
Total amortized cost	323,702
Fair value of available-for-sale debt securities by contractual maturity
Total fair value	$ 342,046