Earnings per Unit (Details) - $ / shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2016	Sep. 27, 2015	Sep. 25, 2016	Sep. 27, 2015
Earnings Per Unit [Abstract]
Basic weighted average units outstanding (in shares)	55,948	55,770	55,922	55,721
Effect of Dilutive Units [Abstract]
Deferred units (in shares)	33	21	30	15
Performance Units (in shares)	0	0	43	9
Restricted units (in shares)	253	365	266	271
Unit options (in shares)	131	126	131	102
Phantom units (in shares)	0	0	0	23
Diluted weighted average units outstanding (in shares)	56,365	56,282	56,392	56,141
Net income (loss) per limited partner unit - basic (in dollars per share)	$ 3.13	$ 2.94	$ 3.30	$ 2.47
Net income (loss) per limited partner unit - diluted (in dollars per share)	$ 3.10	$ 2.92	$ 3.27	$ 2.46