Related Party Transactions (Details) (USD $)	3 Months Ended		9 Months Ended											12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 SIGI	Sep. 30, 2012 SIGI	Sep. 30, 2013 Roger Newnham	Sep. 30, 2012 Roger Newnham	Sep. 30, 2013 Lemmie Rockford	Sep. 30, 2012 Lemmie Rockford	Sep. 30, 2013 Quality RE Partners item	Sep. 30, 2013 Pluris, LLC	Sep. 30, 2012 Pluris, LLC	Dec. 31, 2010 Pluris, LLC
Related party transactions
Lease payments to related party	$ 379,000	$ 327,000	$ 1,176,000	$ 975,000	$ 688,000	$ 695,000	$ 223,000	$ 212,000	$ 68,000	$ 68,000	$ 198,000
Amount of the agreement to construct a wastewater facility for Pluris, LLC														6,100,000
Related party revenues recognized												0	362,000
Net income	$ 23,193,000	$ 17,948,000	$ 49,126,000	$ 40,335,000								$ 0
Number of former shareholders owning leased property											3
Number of current employees owning leased property											2