Cash Equivalents and Investments - Schedule of Investments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Investments [Line Items]
Short-Term	$ 7,568	$ 6,457
Long-Term	58,076	57,511
Municipal Debt Securities [Member]
Schedule of Investments [Line Items]
Short-Term	7,075	5,492
Long-Term	35,580	34,495
Federal Home Loan Securities [Member]
Schedule of Investments [Line Items]
Long-Term	22,248	22,520
Certificates of Deposit [Member]
Schedule of Investments [Line Items]
Short-Term	493	965
Long-Term	$ 248	$ 496