Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt	$ 23.8	$ 12.7
MediaAlpha
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt	23.8	12.7
MediaAlpha | Previous MediaAlpha Bank Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt	0.0	12.7
MediaAlpha | Fair value | MediaAlpha Bank Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, fair value	23.9	0.0
MediaAlpha | Fair value | Previous MediaAlpha Bank Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, fair value	0.0	13.0
MediaAlpha | Carrying Value | MediaAlpha Bank Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt	23.8	0.0
MediaAlpha | Carrying Value | Previous MediaAlpha Bank Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt	$ 0.0	$ 12.7