Investments - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015
Schedule of Available-for-sale Securities [Line Items]
Investments maximum maturity period	5 years
Unrealized (loss) gain, net of unrealized gains/losses, on the investments in the bond portfolio	$ (109)	$ (145)
Guarantee Payment Of Insurance Claims
Schedule of Available-for-sale Securities [Line Items]
Letters of credit outstanding	61,110
Current Investments
Schedule of Available-for-sale Securities [Line Items]
Investments providing collateral for letters of credit to guarantee insurance claims	66,560
Non-Current Investments
Schedule of Available-for-sale Securities [Line Items]
Investments providing collateral for letters of credit to guarantee insurance claims	1,340
Total non-current investments	$ 42,859