Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Significant Accounting Policies [Line Items]
Trade accounts payable	$ 443,000	$ 495,000
Depreciation expense	8,413,000	7,448,000	6,272,000
Goodwill, carrying amount	9,730,000	9,730,000	9,730,000
Goodwill, impairment loss	0
Cash and cash equivalents	28,559,000	7,999,000	24,590,000	10,670,000
Money market mutual fund	2,600,000
Cash and cash equivalents, held in depository accounts	26,000,000
Uninsured Cash and Cash Equivalents	27,000,000
Allowances for doubtful accounts	$ 86,000	$ 47,000
Maximum
Significant Accounting Policies [Line Items]
Cash equivalents, original maturities	90 days
Credit Concentration Risk | Accounts Receivable
Significant Accounting Policies [Line Items]
Largest customer, percentage of accounts receivable	8.20%	16.30%	6.70%
Patents and licenses | Maximum
Significant Accounting Policies [Line Items]
Patents and licenses, useful lives	20 years
Patents and licenses | Minimum
Significant Accounting Policies [Line Items]
Patents and licenses, useful lives	7 years