Segments - Summarized Financial Information Concerning Reportable Segments (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2013	Sep. 30, 2012	Sep. 29, 2013	Sep. 30, 2012
Summarized Financial Information [Abstract]
Segment operating earnings	$ 11,159	$ 7,682	$ 24,764	$ 19,158
Insurance recovery for property damage - casualties				1,769
EMS [Member]
Summarized Financial Information [Abstract]
Segment operating earnings	983	2,375	(1,182)	5,468
Insurance recovery for property damage - casualties				$ 1,769