Fair Value Measurements and Marketable Securities - Summary of Company's Available-for-Sale Securities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	$ 74,726	$ 59,808
Unrealized Gain	38	18
Unrealized Loss	(10)	(7)
Fair Value	74,754	59,819
Money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	4,285	5,886
Unrealized Gain
Unrealized Loss
Fair Value	4,285	5,886
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	1,584	1,185
Unrealized Gain
Unrealized Loss
Fair Value	1,584	1,185
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	49,001	20,237
Unrealized Gain	25	6
Unrealized Loss	(7)	(1)
Fair Value	49,019	20,242
Government securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	21,722	27,893
Unrealized Gain	12	12
Unrealized Loss	(3)	(6)
Fair Value	21,731	27,899
Municipal securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	2,814
Unrealized Gain	1
Unrealized Loss
Fair Value	2,815
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	2,599	15,613
Unrealized Gain
Unrealized Loss
Fair Value	2,599	15,613
Marketable securities including cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	82,005	70,814
Unrealized Gain	38	18
Unrealized Loss	(10)	(7)
Fair Value	82,033	70,825
Less cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	7,279	11,006
Unrealized Gain
Unrealized Loss
Fair Value	$ 7,279	$ 11,006