Intangible Assets - Finite Lived Intangible Assets (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Finite-Lived Intangible Assets [Line Items]
Total amortized intangible assets, Gross Value	$ 34,370,000	$ 34,370,000	$ 34,370,000	$ 34,370,000	$ 34,370,000
Total amortized intangible assets, Accumulated Amortization	(13,744,000)	(10,574,000)	(13,744,000)	(10,574,000)	(11,574,000)
Total amortized intangible assets, Net Value	20,626,000	23,796,000	20,626,000	23,796,000	22,796,000
Amortization expense	1,000,000	500,000	2,100,000	1,000,000
Future amortization expense, Remainder of Fiscal Year	1,600,000		1,600,000
Future amortization expense, Year One	1,300,000		1,300,000
Future amortization expense, Year Two	1,100,000		1,100,000
Future amortization expense, Year Three	1,100,000		1,100,000
Future amortization expense, Year Four	1,000,000		1,000,000
Future amortization expense, after Year Four	14,500,000		14,500,000
Permits [Member]
Finite-Lived Intangible Assets [Line Items]
Total amortized intangible assets, Gross Value	29,713,000	29,713,000	29,713,000	29,713,000	29,713,000
Total amortized intangible assets, Accumulated Amortization	(9,494,000)	(6,837,000)	(9,494,000)	(6,837,000)	(7,573,000)
Total amortized intangible assets, Net Value	20,219,000	22,876,000	20,219,000	22,876,000	22,140,000
Customer Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Total amortized intangible assets, Gross Value	2,198,000	2,198,000	2,198,000	2,198,000	2,198,000
Total amortized intangible assets, Accumulated Amortization	(2,056,000)	(1,828,000)	(2,056,000)	(1,828,000)	(1,942,000)
Total amortized intangible assets, Net Value	142,000	370,000	142,000	370,000	256,000
Covenants not to compete [Member]
Finite-Lived Intangible Assets [Line Items]
Total amortized intangible assets, Gross Value	1,588,000	1,588,000	1,588,000	1,588,000	1,588,000
Total amortized intangible assets, Accumulated Amortization	(1,536,000)	(1,401,000)	(1,536,000)	(1,401,000)	(1,476,000)
Total amortized intangible assets, Net Value	52,000	187,000	52,000	187,000	112,000
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Total amortized intangible assets, Gross Value	871,000	871,000	871,000	871,000	871,000
Total amortized intangible assets, Accumulated Amortization	(658,000)	(508,000)	(658,000)	(508,000)	(583,000)
Total amortized intangible assets, Net Value	$ 213,000	$ 363,000	$ 213,000	$ 363,000	$ 288,000