Fair Value Measurements - Schedule of Fair Value Hierarchy of Financial Assets and Liabilities Carried at Fair Value and Measured on Recurring Basis (Detail) - Fair value measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	$ 3,421	$ 2,951
Cash equivalents:
Total cash equivalents	10,139
Debt securities:
Available-for-sale debt securities	7,101
Total assets at fair value	17,240	16,711
Contingent consideration liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	3,421	2,951
U.S. government securities [Member]
Cash equivalents:
Total cash equivalents	2,749
Debt securities:
Available-for-sale debt securities	2,000	11,301
Money market and other funds [Member]
Cash equivalents:
Total cash equivalents	4,090	5,410
Commercial paper [Member]
Cash equivalents:
Total cash equivalents	1,999
Debt securities:
Available-for-sale debt securities	1,998
Time deposits [Member]
Debt securities:
Available-for-sale debt securities	807
Taxable municipal bonds [Member]
Cash equivalents:
Total cash equivalents	1,301
Debt securities:
Available-for-sale debt securities	2,296
Quoted prices in active markets using identical assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	0	0
Quoted prices in active markets using identical assets (Level 1) [Member] | Contingent consideration liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	0	0
Significant other observable inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	0	0
Cash equivalents:
Total cash equivalents	10,139
Debt securities:
Available-for-sale debt securities	7,101
Total assets at fair value	17,240	16,711
Significant other observable inputs (Level 2) [Member] | Contingent consideration liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	0	0
Significant other observable inputs (Level 2) [Member] | U.S. government securities [Member]
Cash equivalents:
Total cash equivalents	2,749
Debt securities:
Available-for-sale debt securities	2,000	11,301
Significant other observable inputs (Level 2) [Member] | Money market and other funds [Member]
Cash equivalents:
Total cash equivalents	4,090	5,410
Significant other observable inputs (Level 2) [Member] | Commercial paper [Member]
Cash equivalents:
Total cash equivalents	1,999
Debt securities:
Available-for-sale debt securities	1,998
Significant other observable inputs (Level 2) [Member] | Time deposits [Member]
Debt securities:
Available-for-sale debt securities	807
Significant other observable inputs (Level 2) [Member] | Taxable municipal bonds [Member]
Cash equivalents:
Total cash equivalents	1,301
Debt securities:
Available-for-sale debt securities	2,296
Significant unobservable inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	3,421	2,951
Significant unobservable inputs (Level 3) [Member] | Contingent consideration liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	$ 3,421	$ 2,951