Employee Benefit Plans - Multiemployer Pension Plan (Details)	12 Months Ended
	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Minimum percent of total contributions to the multiemployer plan to require disclosure	5.00%
Zone Status, Less than 65% [Member]
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plans Certified Zone Status Percentages	65.00%
Zone Status, Less than 80% [Member]
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plans Certified Zone Status Percentages	80.00%
Zone Status, At Least 80% [Member]
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plans Certified Zone Status Percentages	80.00%