Intangible Assets - Finite Lived Intangible Assets (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 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	(14,938,000)	(11,074,000)	(14,938,000)	(11,074,000)	(11,574,000)
Total amortized intangible assets, Net Value	19,432,000	23,296,000	19,432,000	23,296,000	22,796,000
Amortization expense	1,200,000	500,000	3,300,000	1,500,000
Future amortization expense, Remainder of Fiscal Year	400,000		400,000
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	(10,588,000)	(7,205,000)	(10,588,000)	(7,205,000)	(7,573,000)
Total amortized intangible assets, Net Value	19,125,000	22,508,000	19,125,000	22,508,000	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	(2,113,000)	(1,885,000)	(2,113,000)	(1,885,000)	(1,942,000)
Total amortized intangible assets, Net Value	85,000	313,000	85,000	313,000	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	(1,541,000)	(1,439,000)	(1,541,000)	(1,439,000)	(1,476,000)
Total amortized intangible assets, Net Value	47,000	149,000	47,000	149,000	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	(696,000)	(545,000)	(696,000)	(545,000)	(583,000)
Total amortized intangible assets, Net Value	$ 175,000	$ 326,000	$ 175,000	$ 326,000	$ 288,000