Earnings per Unit (Details) - $ / shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 24, 2018	Jun. 30, 2019	Jun. 24, 2018
Earnings Per Unit [Abstract]
Basic weighted average units outstanding (in shares)	56,474	56,231	56,334	56,192
Effect of dilutive units:
Deferred units (in shares)	47	46	0	0
Restricted units (in shares)	243	277	0	0
Unit options (in shares)	122	173	0	0
Diluted weighted average units outstanding (in shares)	56,886	56,727	56,334	56,192
Net income (loss) per unit - basic (in dollars per share)	$ 1.12	$ 0.34	$ (0.36)	$ (1.14)
Net income (loss) per unit - diluted (in dollars per share)	$ 1.11	$ 0.34	$ (0.36)	$ (1.14)