Cash, Cash Equivalents and Short-Term Investments and Long-Term Investments (Detail) - USD ($) $ in Thousands	Jul. 01, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 41,379	$ 48,260
Unrealized Holdings Gains		1
Unrealized Holdings Losses	19	23
Fair Value	41,360	48,238
Cash and Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	19,575	27,043
Fair Value	19,575	27,043
Cash and Cash Equivalents | Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	999
Fair Value	999
Cash and Cash Equivalents | U.S. treasury and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	749
Fair Value	749
Cash and Cash Equivalents | Cash
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,730	18,726
Fair Value	11,730	18,726
Cash and Cash Equivalents | Money market funds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6,097	8,317
Fair Value	6,097	8,317
Short-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,223	17,610
Unrealized Holdings Losses	6	8
Fair Value	14,217	17,602
Short-term Investments | Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	510	600
Unrealized Holdings Losses	1
Fair Value	509	600
Short-term Investments | U.S. treasury and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,519	6,432
Unrealized Holdings Losses		1
Fair Value	3,519	6,431
Short-term Investments | Corporate bonds and medium-term notes
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6,200	8,586
Unrealized Holdings Losses	5	6
Fair Value	6,195	8,580
Short-term Investments | Certificate of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,500
Fair Value	2,500
Short-term Investments | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,494	1,992
Unrealized Holdings Losses		1
Fair Value	1,494	1,991
Other Long-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,581	3,607
Unrealized Holdings Gains		1
Unrealized Holdings Losses	13	15
Fair Value	7,568	3,593
Other Long-term Investments | Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	500	500
Unrealized Holdings Losses	3	4
Fair Value	497	496
Other Long-term Investments | U.S. treasury and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,595	597
Unrealized Holdings Gains		1
Unrealized Holdings Losses	2
Fair Value	2,593	598
Other Long-term Investments | Corporate bonds and medium-term notes
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,486	2,510
Unrealized Holdings Losses	8	11
Fair Value	$ 4,478	$ 2,499