Investments in Unconsolidated Investees (Combined Operating Results) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Schedule of financial data of unconsolidated investees, Combined Operating Results
Earnings from unconsolidated investee	$ 1,408	$ 1,161	$ 3,142	$ 2,239
Alliance-HNI, LLC and Subsidiaries [Member]
Schedule of financial data of unconsolidated investees, Combined Operating Results
Revenues	4,583	4,243	9,081	8,578
Expenses	2,341	2,460	4,318	4,999
Net income	2,242	1,783	4,763	3,579
Earnings from unconsolidated investee	1,106	893	2,382	1,791
Austin Cyberknife, Llc [Member]
Schedule of financial data of unconsolidated investees, Combined Operating Results
Revenues	2,376	2,056	4,245	3,471
Expenses	785	718	1,504	1,382
Net income	1,591	1,338	2,741	2,089
Earnings from unconsolidated investee	239	200	412	313
Unconsolidated Investees, Including Alliance-HNI, LLC and Subsidiaries and Austin Cyberknife [Member]
Schedule of financial data of unconsolidated investees, Combined Operating Results
Revenues	7,272	7,488	14,009	14,458
Expenses	3,315	4,475	6,906	8,992
Net income	3,957	3,013	7,103	5,466
Earnings from unconsolidated investee	$ 1,409	$ 1,162	$ 2,951	$ 2,240