Statement of Cash Flow Information - Non-Cash Additions and Non-Cash Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Nonmonetary Transaction
Non-monetary exchanges related to resale licensing revenue	$ 0	$ 250
Non-cash revenue	5	289
Acquisition revenue on underwriting [Member]
Nonmonetary Transaction
Non-cash revenue	0	39
Licensing revenue from specific data licenses and selections [Member]
Nonmonetary Transaction
Non-cash revenue	0	250
Solutions and other revenue recognized [Member]
Nonmonetary Transaction
Non-cash revenue	$ 5	$ 0