Description of Business and Basis of Presentation Patent Acquisition (Details) - patents	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of patent portfolios acquired	1	2	3	6	25