Investments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 26, 2015	Dec. 27, 2014
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	$ (145,000)	$ 163,000
Guarantee Payment Of Insurance Claims
Schedule of Available-for-sale Securities [Line Items]
Letters of credit outstanding	57,610,000
Current Investments
Schedule of Available-for-sale Securities [Line Items]
Investments providing collateral for letters of credit to guarantee insurance claims	48,823,000
Non-Current Investments
Schedule of Available-for-sale Securities [Line Items]
Investments providing collateral for letters of credit to guarantee insurance claims	15,188,000
Total non-current investments	$ 59,261,000