Selling Arrangement - News America Marketing (Details) - Customer Contracts [Member] - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2011
Finite-Lived Intangible Assets [Line Items]
Payment for arrangement to sell signs			$ 4,000,000
Term of arrangement			10 years
Amortization expense	$ 400,000	$ 400,000
2017	400,000
2018	400,000
2019	400,000
2020	400,000
2021	$ 117,000