Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Changes in balances of each component of accumulated other comprehensive income, net of taxes [Roll Forward]
Beginning balance	$ 19,571
Other comprehensive income (loss) before reclassifications	(1,368)
Amounts reclassified from accumulated other comprehensive income	(441)
Net current-period other comprehensive income (loss)	(1,809)	(1,463)
Ending balance	17,762
Unrealized Gains on Available-for-Sale Securities [Member]
Changes in balances of each component of accumulated other comprehensive income, net of taxes [Roll Forward]
Beginning balance	19,663
Other comprehensive income (loss) before reclassifications	(1,460)
Amounts reclassified from accumulated other comprehensive income	(441)
Net current-period other comprehensive income (loss)	(1,901)
Ending balance	17,762
Derivative Financial Instrument [Member]
Changes in balances of each component of accumulated other comprehensive income, net of taxes [Roll Forward]
Beginning balance	(92)
Other comprehensive income (loss) before reclassifications	92
Amounts reclassified from accumulated other comprehensive income	0
Net current-period other comprehensive income (loss)	92
Ending balance	$ 0

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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-Name Statement of Financial Accounting Standard (FAS)

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 31

-Article 5

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-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 10

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+ Details

- Definition

Net of tax amount of other comprehensive income (loss) attributable to the parent entity.

+ References

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-Name Accounting Research Bulletin (ARB)

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+ Details