Investments - Investments in Continuous Unrealized Loss Position for Less Than Twelve Months (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 30,332	$ 36,271
Unrealized Losses	(30)	(30)
Municipal bonds and notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value		1,499
Unrealized Losses		(1)
Corporate bonds and notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	30,332	34,772
Unrealized Losses	$ (30)	$ (29)