Multiemployer Pension (Details) (Multiemployer pension, WAPA PR, USD $)	3 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 item	Dec. 31, 2011 Maximum	Jun. 30, 2013 Beginning on January 1, 2013	Jun. 30, 2013 Beginning on January 1, 2014	Jun. 30, 2013 Beginning on January 1, 2015
Multiemployer pension
Number of collective bargaining agreements		2
Increase in the contribution rate agreed by the company under the "preferred schedule" of the Rehabilitation Plan (as a percent)				3.00%	3.00%	3.00%
Period beginning on the effective date of the MOA during which withdrawal from the plan would result in additional contribution due to the unfunded vested benefits		5 years
Surcharge in the initial year (as a percent)		5.00%
Surcharge for each successive year, thereafter, the plan is in critical status (as a percent)		10.00%
Total contributions made to the Plan			5.00%
Contributions	$ 32,611	$ 62,843