Investments Held in Rabbi Trust - Components of Investment Income (Losses), Included in Other Income (Expense) in Accompanying Consolidated Statements of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Investments Debt And Equity Securities [Abstract]
Gross realized gains from sale of trading securities	$ 3	$ 96
Gross realized (losses) from sale of trading securities		(3)
Dividend and interest income	9	10
Net unrealized holding gains (losses)	75	195
Net investment income (losses)	$ 87	$ 298