Fair Value Measurements and Other-Than-Temporary Impairments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (Fair value, measurements, recurring [Member], USD $) In Thousands, unless otherwise specified	Dec. 27, 2014	Dec. 28, 2013
Assets
Total Assets	$ 325,705	$ 296,877
Money market funds [Member]
Assets
Total Assets	21,478	51,749
Certificates of deposit [Member]
Assets
Total Assets	8,060	3,840
Commercial paper [Member]
Assets
Total Assets	46,072	85,860
Corporate bonds [Member]
Assets
Total Assets	235,285	150,595
U.S. treasuries [Member]
Assets
Total Assets	14,810	4,804
Foreign currency exchange forward contracts [Member]
Assets
Total Assets	0	29
Liabilities
Total Liabilities	(64)	(26)
Level 1 [Member]
Assets
Total Assets	36,288	56,553
Level 1 [Member] | Money market funds [Member]
Assets
Total Assets	21,478	51,749
Level 1 [Member] | Certificates of deposit [Member]
Assets
Total Assets	0	0
Level 1 [Member] | Commercial paper [Member]
Assets
Total Assets	0	0
Level 1 [Member] | Corporate bonds [Member]
Assets
Total Assets	0	0
Level 1 [Member] | U.S. treasuries [Member]
Assets
Total Assets	14,810	4,804
Level 1 [Member] | Foreign currency exchange forward contracts [Member]
Assets
Total Assets	0	0
Liabilities
Total Liabilities	0	0
Level 2 [Member]
Assets
Total Assets	289,417	240,324
Level 2 [Member] | Money market funds [Member]
Assets
Total Assets	0	0
Level 2 [Member] | Certificates of deposit [Member]
Assets
Total Assets	8,060	3,840
Level 2 [Member] | Commercial paper [Member]
Assets
Total Assets	46,072	85,860
Level 2 [Member] | Corporate bonds [Member]
Assets
Total Assets	235,285	150,595
Level 2 [Member] | U.S. treasuries [Member]
Assets
Total Assets	0	0
Level 2 [Member] | Foreign currency exchange forward contracts [Member]
Assets
Total Assets	0	29
Liabilities
Total Liabilities	(64)	(26)
Level 3 [Member]
Assets
Total Assets	0	0
Level 3 [Member] | Money market funds [Member]
Assets
Total Assets	0	0
Level 3 [Member] | Certificates of deposit [Member]
Assets
Total Assets	0	0
Level 3 [Member] | Commercial paper [Member]
Assets
Total Assets	0	0
Level 3 [Member] | Corporate bonds [Member]
Assets
Total Assets	0	0
Level 3 [Member] | U.S. treasuries [Member]
Assets
Total Assets	0	0
Level 3 [Member] | Foreign currency exchange forward contracts [Member]
Assets
Total Assets	0	0
Liabilities
Total Liabilities	$ 0	$ 0