Credit Arrangements (Details)	9 Months Ended		9 Months Ended	0 Months Ended		9 Months Ended	0 Months Ended			9 Months Ended						9 Months Ended			9 Months Ended		9 Months Ended
	Sep. 30, 2013 Senior Notes USD ($)	Dec. 28, 2012 Senior Notes USD ($)	Sep. 30, 2013 Senior Notes Minimum USD ($)	Jul. 25, 2013 Notes Agreement USD ($) item	Dec. 28, 2012 Notes Agreement USD ($)	Sep. 30, 2013 Notes Agreement Minimum	Dec. 28, 2012 Notes Agreement Maximum USD ($)	Dec. 31, 2010 Subordinated Promissory Note Rockford USD ($)	Dec. 18, 2009 Subordinated Promissory Note James Construction Group LLC USD ($)	Sep. 30, 2013 Credit Agreement LIBOR	Sep. 30, 2013 Credit Agreement Base rate	Sep. 30, 2013 Credit Agreement Federal funds rate	Sep. 30, 2013 Credit Agreement Prime rate	Sep. 30, 2013 Credit Agreement Minimum	Sep. 30, 2013 Credit Agreement Revolving line of credit USD ($)	Sep. 30, 2013 Credit Agreement Revolving line of credit Minimum USD ($)	Sep. 30, 2013 Credit Agreement Commercial letters of credit USD ($)	Dec. 31, 2012 Credit Agreement Commercial letters of credit USD ($)	Sep. 30, 2013 Canadian Credit Facility Commercial letters of credit CAD	Dec. 31, 2012 Canadian Credit Facility Commercial letters of credit CAD	Sep. 30, 2013 Canadian Credit Facility Commercial letters of credit Maximum	Oct. 29, 2009 Agreement with Private Bank and Trust Company USD ($)
Credit arrangements
Maximum borrowing capacity															$ 75,000,000		$ 75,000,000		10,000,000
Incremental maximum borrowing capacity															50,000,000
Variable rate basis										LIBOR	Base Rate	Federal Funds Rate	prime rate
Basis spread on variable rate (as a percent)												0.50%
Prepayment to be paid on debt			5,000,000													5,000,000
Interest rate (as a percent)	3.65%			3.85%
Restrictions on investments, change of control provisions and provisions as a percentage of total assets to be disposed off						20.00%								20.00%
Total commercial letters of credit outstanding																	4,808,000	4,808,000	3,410,000	1,364,000
Available borrowing capacity															70,192,000				6,590,000
Borrowings to be incurred prior to December 28, 2016							25,000,000
Borrowings outstanding															0							0
Term of credit facility																					5 years
Annual fee (as a percent)																			1.00%
Required principal payment	7,100,000			3,600,000
Initial principal amount		$ 50,000,000		$ 25,000,000	$ 25,000,000			$ 16,712,000	$ 53,500,000
Number of annual principal payments				7