Fair Value Measurement - Summary of Fair Value Measurements of Cash Equivalents, Available-for-Sale Securities and Contingent Consideration Liability (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and available-for-sale securities	$ 124,225	$ 128,224
Total contingent consideration liabilities	1,620	1,570
Money market funds [Member] | Cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and available-for-sale securities	7,234	6,934
U.S. government sponsored entity debt securities [Member] | Cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and available-for-sale securities	116,991	121,290
Contingent consideration liability [Member]
Schedule of Available-for-sale Securities [Line Items]
Total contingent consideration liabilities	1,620	1,570
Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and available-for-sale securities	7,234	6,934
Total contingent consideration liabilities	0
Level 1 [Member] | Money market funds [Member] | Cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and available-for-sale securities	7,234	6,934
Level 1 [Member] | U.S. government sponsored entity debt securities [Member] | Cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and available-for-sale securities	0
Level 1 [Member] | Contingent consideration liability [Member]
Schedule of Available-for-sale Securities [Line Items]
Total contingent consideration liabilities	0
Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and available-for-sale securities	116,991	121,290
Total contingent consideration liabilities	0
Level 2 [Member] | Money market funds [Member] | Cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and available-for-sale securities	0
Level 2 [Member] | U.S. government sponsored entity debt securities [Member] | Cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and available-for-sale securities	116,991	121,290
Level 2 [Member] | Contingent consideration liability [Member]
Schedule of Available-for-sale Securities [Line Items]
Total contingent consideration liabilities	0
Level 3 [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and available-for-sale securities	0
Total contingent consideration liabilities	1,620	1,570
Level 3 [Member] | Money market funds [Member] | Cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and available-for-sale securities	0
Level 3 [Member] | U.S. government sponsored entity debt securities [Member] | Cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and available-for-sale securities	0
Level 3 [Member] | Contingent consideration liability [Member]
Schedule of Available-for-sale Securities [Line Items]
Total contingent consideration liabilities	$ 1,620	$ 1,570