Amortized Costs and Fair Values (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Equity securities, Amortized costs	$ 10,870	$ 5,005
Total, Amortized costs	481,083	449,552
Debt securities, Fair values	492,186
Equity securities, Fair values	11,073	5,443
Available for sale securities, Total	503,259	460,985
Municipal
Schedule of Available-for-sale Securities [Line Items]
Debt securities, Amortized costs	18,012	26,721
Debt securities, Fair values	19,011	27,801
Corporate and utilities
Schedule of Available-for-sale Securities [Line Items]
Debt securities, Amortized costs	268,874	237,912
Debt securities, Fair values	287,528	244,123
Foreign
Schedule of Available-for-sale Securities [Line Items]
Debt securities, Amortized costs	168,084	162,384
Debt securities, Fair values	169,009	164,268
U.S. Government
Schedule of Available-for-sale Securities [Line Items]
Debt securities, Amortized costs	15,243	17,530
Debt securities, Fair values	$ 16,638	$ 19,350

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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+ Details

- Definition

This item represents the cost of debt and equity 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.

+ References+ Details

- Definition

Amount of debt securities categorized neither as held-to-maturity nor trading.

+ References

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Amount of equity securities categorized neither as held-to-maturity nor as trading.

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+ Details