Executive Benefit Agreements and Employee Savings Plans - Life Insurance Policies (Parenthetical) (Detail) (USD $)			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Death Benefit 2005 Agreement [Member]
Executive Benefit Agreements and Employee Savings Plans [Line Items]
Face value of life insurance policies for CEO	$ 21,242,000	$ 21,522,000	$ 7,000,000
Amount paid to CEO's designated beneficiary under 2005 Agreement			$ 2,500,000