Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Consolidated Statements of Comprehensive Income [Abstract]
Net Income	$ 25,402us-gaap_NetIncomeLoss	$ 24,061us-gaap_NetIncomeLoss	$ 23,349us-gaap_NetIncomeLoss
Other Comprehensive Income (Loss)
Increase (Decrease) in Net Unrealized Gain (Loss) on Available-for-Sale Securities	8,719	(16,564)	4,182
Deferred Tax (Expense) Benefit Related to Unrealized Gains (Losses)	(3,666)	6,965	(1,759)
Reclassification Adjustment for Realized (Gain) Loss on Available-for-Sale Securities Included in Net Income	(90)	229	(158)
Tax Expense (Benefit) Related to Reclassification Adjustment	38	(97)	67
Change in Net Unrealized Gain (Loss) on Available-for-Sale Securities, Net of Tax	5,001	(9,467)	2,332
Total Other Comprehensive Income (Loss)	5,001	(9,467)	2,332
Comprehensive Income	$ 30,403us-gaap_ComprehensiveIncomeNetOfTax	$ 14,594us-gaap_ComprehensiveIncomeNetOfTax	$ 25,681us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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