Summary of significant accounting policies (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012 Concourse Communications Detroit, LLC	Dec. 31, 2012 Chicago Concourse Development Group, LLC
Principles of consolidation
Percentage of ownership in subsidiaries		70.00%	70.00%
Reclassifications
Reclassification from other assets to intangible assets	$ 335,000
Impact of Reclassification on Net Income	0
Impact of Reclassification on Stockholders Equity	$ 0