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Fair Value of Financial Instruments (Details) - USD ($) $ in Millions | Mar. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Fair Value, Balance Sheet Grouping, Financial Statement Captions |  |
Debt | $ 195.4 | $ 192.7
NSM Holding Co LLC |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions |  |
Debt | 184.5 | 178.5
NSM Holding Co LLC | NSM Bank Facility |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions |  |
Debt | 182.8 | 176.6
NSM Holding Co LLC | Carrying Value | NSM Bank Facility |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions |  |
Debt | 182.8 | 176.6
NSM Holding Co LLC | Estimate of Fair Value Measurement | NSM Bank Facility |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions |  |
Debt instrument, fair value disclosure | 182.9 | 176.1
MediaAlpha |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions |  |
Debt | 0.0 | 14.2
MediaAlpha | MediaAlpha Bank Facility |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions |  |
Debt | 0.0 | 14.2
MediaAlpha | Carrying Value | MediaAlpha Bank Facility |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions |  |
Debt | 0.0 | 14.2
MediaAlpha | Estimate of Fair Value Measurement | MediaAlpha Bank Facility |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions |  |
Debt instrument, fair value disclosure | 0.0 | 14.6
Other Operations | Carrying Value |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions |  |
Debt | 10.9 | 0.0
Other Operations | Estimate of Fair Value Measurement |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions |  |
Debt instrument, fair value disclosure | $ 10.9 | $ 0.0

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- Definition Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611 + Details
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- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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