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Income Taxes (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes
Income tax expense differences from the amount computed by applying the U.S. Federal income tax rate to income before income taxes (as a percent)	35.00%	35.00%	35.00%
Reasons for the difference of income tax expense
Computed expected tax expense	$ 64,183	$ 55,634	$ 66,941
Change in taxes resulting from:
Tax-exempt interest income	(4,828)	(4,381)	(3,682)
State tax, net of federal income taxes and tax credit	(110)	1,446	3,302
Tax refunds	(966)
Other investment income	(2,656)	(2,691)	(3,083)
Other	616	557	600
Total income taxes	$ 56,239	$ 50,565	$ 64,078

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the current period and the expected income tax expense or benefit computed attributable to other investment income.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to deductions. Including, but not limited to, extraterritorial income exclusion deduction, qualified production activity deduction, dividend deduction, deduction for dividend paid to employee stock ownership plan, Medicare prescription drug benefit subsidy deduction, and other deductions.

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