Information Pertaining to Held to Maturity Securities With Gross Unrealized Losses (Detail) (Corporate Bond, USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Corporate Bond
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months Fair Value	$ 30,327	$ 22,785
Less than 12 months Gross Unrealized Losses	(55)	(41)
12 months or longer Fair Value
12 months or longer Gross Unrealized Losses
Total Fair Value	30,327	22,785
Total Gross Unrealized Losses	$ (55)	$ (41)

This item represents the excess of amortized cost basis over fair value of securities that have been in a loss position for twelve months or longer for those securities which are categorized as held-to-maturity.

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This item represents the excess of amortized cost basis over fair value of securities in a loss position and which are categorized as held-to-maturity.

+ References+ Details

- Definition

This item represents the fair value of securities categorized as held-to-maturity which are in an unrealized loss position.

+ References+ Details

- Definition

This item represents the excess of amortized cost basis over fair value of securities that have been in a loss position for less than twelve months for those securities which are categorized as held-to-maturity.

+ References+ Details

- Definition

This item represents the fair value of securities categorized as held-to-maturity that have been in a continuous unrealized loss position for less than twelve months.

+ References+ Details

- Definition

This item represents the fair value of securities categorized as held-to-maturity securities that have been in a continuous unrealized loss position for twelve months or longer.

+ References+ Details