Related Party Transactions (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Related Party Transaction [Line Items]
Percentage of equity interest (in hundredths)	19.90%		19.90%
Amount of equity investment	$ 1,200,000	$ 1,500,000	$ 1,200,000	$ 1,500,000
Equity in earnings	97,000	260,000	332,000	359,000
Cash distribution from earnings of related party			312,000	761,000
Purchases from W&B	0	3,600,000	0	3,600,000
Maintenance and repair services, accessories and parts invoiced from related party	$ 359,000	$ 370,000	$ 899,000	$ 647,000