Investments (Details 4) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Fair Value of Securities with Gross Unrealized Loss	$ 29,598	$ 27,035
Gross Unrealized Losses	(501)	(350)
Less than 5% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses	(435)	(252)
5% to 10% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses
Greater than 10% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses	(66)	(98)
Three months [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Fair Value of Securities with Gross Unrealized Loss	6,572	26,121
Gross Unrealized Losses	(121)	(266)
Three months [Member] | Less than 5% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses	(121)	(246)
Three months [Member] | 5% to 10% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses
Three months [Member] | Greater than 10% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses		(20)
Six months [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Fair Value of Securities with Gross Unrealized Loss	22,114
Gross Unrealized Losses	(325)
Six months [Member] | Less than 5% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses	(309)
Six months [Member] | 5% to 10% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses
Six months [Member] | Greater than 10% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses	(16)
Nine months [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Fair Value of Securities with Gross Unrealized Loss
Gross Unrealized Losses
Severity of Gross Unrealized Losses
Nine months [Member] | Less than 5% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses
Nine months [Member] | 5% to 10% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses
Nine months [Member] | Greater than 10% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses
Twelve months[Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Fair Value of Securities with Gross Unrealized Loss		702
Gross Unrealized Losses		(6)
Twelve months[Member] | Less than 5% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses		(6)
Twelve months[Member] | 5% to 10% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses
Greater than 12 months [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Fair Value of Securities with Gross Unrealized Loss	912	212
Gross Unrealized Losses	(55)	(78)
Greater than 12 months [Member] | Less than 5% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses	(5)
Greater than 12 months [Member] | 5% to 10% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses
Greater than 12 months [Member] | Greater than 10% [Member]
Gross unrealized losses by current severity and length of time that individual securities have been in a continuous unrealized loss position
Severity of Gross Unrealized Losses	$ (50)	$ (78)