Significant Accounting Policies - Fair Value of the Company's Investments by Type (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Amortized Cost	$ 19,421	$ 15,775
Accrued Interest	48	57
Gross Unrealized Gains	5	27
Gross Unrealized Losses	1
Estimated Fair Value	19,473	15,859
Level 2 [Member] | Obligations of U.S. Government and its Agencies [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Amortized Cost	4,899	3,505
Accrued Interest	1	6
Gross Unrealized Gains	1	2
Gross Unrealized Losses
Estimated Fair Value	4,901	3,513
Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Amortized Cost	8,528	4,035
Accrued Interest	47	22
Gross Unrealized Gains	2	6
Gross Unrealized Losses	1
Estimated Fair Value	8,576	4,063
Level 2 [Member] | Commercial Paper [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Amortized Cost	5,994	1,695
Accrued Interest
Gross Unrealized Gains	2	1
Gross Unrealized Losses
Estimated Fair Value	5,996	1,696
Level 2 [Member] | U.S. Treasury Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Amortized Cost		999
Accrued Interest		2
Gross Unrealized Gains		2
Gross Unrealized Losses
Estimated Fair Value		1,003
Level 2 [Member] | Municipal Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Amortized Cost		5,541
Accrued Interest		27
Gross Unrealized Gains		16
Gross Unrealized Losses
Estimated Fair Value		$ 5,584