Intangible Assets - Finite Lived Intangible Assets (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 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
Total amortized intangible assets, Accumulated Amortization	(12,720,000)	(10,074,000)	(11,574,000)
Total amortized intangible assets, Net Value	21,650,000	24,296,000	22,796,000
Amortization expense	1,100,000	500,000
Future amortization expense, Remainder of Fiscal Year	2,600,000
Future amortization expense, Year One	1,300,000
Future amortization expense, Year Two	1,100,000
Future amortization expense, Year Three	1,100,000
Future amortization expense, Year Four	1,100,000
Future amortization expense, after Year Four	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
Total amortized intangible assets, Accumulated Amortization	(8,589,000)	(6,468,000)	(7,573,000)
Total amortized intangible assets, Net Value	21,124,000	23,245,000	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
Total amortized intangible assets, Accumulated Amortization	(2,000,000)	(1,772,000)	(1,942,000)
Total amortized intangible assets, Net Value	198,000	426,000	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
Total amortized intangible assets, Accumulated Amortization	(1,510,000)	(1,364,000)	(1,476,000)
Total amortized intangible assets, Net Value	78,000	224,000	112,000
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Total amortized intangible assets, Gross Value	871,000	871,000	871,000
Total amortized intangible assets, Accumulated Amortization	(621,000)	(470,000)	(583,000)
Total amortized intangible assets, Net Value	$ 250,000	$ 401,000	$ 288,000