GOODWILL AND INTANGIBLE ASSETS - Amortized Intangible Assets - (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 26, 2016	Mar. 28, 2015	Dec. 27, 2014	Dec. 26, 2015
Components of amortized intangible assets
Gross Carrying Amount	$ 214,210			$ 215,939
Accumulated Amortization	114,689			111,672
Amortization expense for intangible assets	3,995	$ 4,913
Estimated amortization expense
2015	15,841
2016	15,754
2017	14,116
2018	13,324
2019	12,283
Customer Relationships
Components of amortized intangible assets
Gross Carrying Amount	199,902			201,801
Accumulated Amortization	$ 104,376			101,614
Weighted Average Life	13 years		13 years
Proprietary Software & Database
Components of amortized intangible assets
Gross Carrying Amount	$ 3,611			3,571
Accumulated Amortization	$ 2,997			2,966
Weighted Average Life	8 years		8 years
Patents & Proprietary Technology
Components of amortized intangible assets
Gross Carrying Amount	$ 6,835			6,815
Accumulated Amortization	$ 3,528			3,421
Weighted Average Life	11 years		11 years
Other
Components of amortized intangible assets
Gross Carrying Amount	$ 3,862			3,752
Accumulated Amortization	$ 3,788			$ 3,671
Weighted Average Life	3 years		3 years