Investments (Details 4) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Investments
Total temporary impairment	$ 4,918	$ 315
Investments in an unrealized loss position
Less than 12 months, Fair Value	111,024	49,580
Less than 12 months, Unrealized Loss	(4,423)	(315)
12 months or more, Fair Value	9,943
12 months or more, Unrealized Loss	(495)
U.S. Agencies
Investments in an unrealized loss position
Number of investments in an unrealized loss position	16	3
Less than 12 months, Fair Value	52,619	9,676
Less than 12 months, Unrealized Loss	(1,362)	(6)
Mortgage-backed securities
Investments in an unrealized loss position
Number of investments in an unrealized loss position	14	11
Less than 12 months, Fair Value	24,746	28,688
Less than 12 months, Unrealized Loss	(600)	(169)
12 months or more, Fair Value	6,203
12 months or more, Unrealized Loss	(173)
Municipal securities
Investments in an unrealized loss position
Number of investments in an unrealized loss position	98	28
Less than 12 months, Fair Value	33,659	11,216
Less than 12 months, Unrealized Loss	(2,461)	(140)
12 months or more, Fair Value	3,740
12 months or more, Unrealized Loss	$ (322)