Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Consolidated Balance Sheets
Fixed maturity securities available for sale, amortized cost (in dollars)	$ 2,249,891	$ 2,315,654
Equity securities available for sale, cost (in dollars)	$ 122,347	$ 94,467
Common stock, average par value (in dollars per share)	$ 5usic_CommonStockAverageParValuePerShare	$ 5usic_CommonStockAverageParValuePerShare
Common stock, shares authorized	1,000,000us-gaap_CommonStockSharesAuthorized	1,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	1,000,000us-gaap_CommonStockSharesIssued	1,000,000us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	1,000,000us-gaap_CommonStockSharesOutstanding	1,000,000us-gaap_CommonStockSharesOutstanding

This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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This item represents the cost of equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments for other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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- Definition

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Represents common stock average per value.

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