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Segment Information (Details) - USD ($) | 3 Months Ended | 10 Months Ended | 12 Months Ended
--- | --- | --- | ---
Dec. 31, 2019 | Sep. 30, 2019 | Jun. 30, 2019 | Mar. 31, 2019 | Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2019 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Segment reporting information |  |  |  |  |  |  |  |  |  |  |  |
Earned insurance premiums |  |  |  |  |  |  |  |  |  | $ 16,300,000 | $ 13,900,000 | $ 10,400,000
Net investment income |  |  |  |  |  |  |  |  |  | 79,700,000 | 59,000,000.0 | 56,000,000.0
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  | 433,200,000 | (108,300,000) | 133,300,000
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  | 318,500,000 |  |
Commission revenues |  |  |  |  |  |  |  |  |  | 249,100,000 | 389,200,000 | 167,000,000.0
Other revenue |  |  |  |  |  |  |  |  |  | 47,600,000 | 15,300,000 | 7,100,000
Total revenues | $ 175,300,000 | $ 155,500,000 | $ 129,000,000.0 | $ 433,600,000 | $ 6,000,000.0 | $ 198,700,000 | $ 122,300,000 | $ 42,100,000 |  | 893,400,000 | 369,100,000 | 373,800,000
Loss and loss adjustment expenses |  |  |  |  |  |  |  |  |  |  |  | 1,100,000
Insurance acquisition expense |  |  |  |  |  |  |  |  |  | 5,700,000 | 5,300,000 | 4,100,000
Other underwriting expenses |  |  |  |  |  |  |  |  |  | 400,000 | 400,000 | 400,000
Change in fair value of contingent consideration earnout liabilities |  |  |  |  |  |  |  |  |  | 2,100,000 | 2,700,000 |
Cost of sales |  |  |  |  |  |  |  |  |  | 48,100,000 | 248,700,000 | 139,400,000
General and administrative expenses |  |  |  |  |  |  |  |  |  | 327,800,000 | 233,500,000 | 208,000,000.0
Broker commission expense |  |  |  |  |  |  |  |  |  | 64,800,000 | 28,400,000 |
Amortization of other intangible assets |  |  |  |  |  |  |  |  |  | 21,800,000 | 18,800,000 | 10,700,000
Interest expense |  |  |  |  |  |  |  |  |  | 17,600,000 | 9,500,000 | 2,300,000
Total expenses | 118,800,000 | 104,400,000 | 113,200,000 | 151,900,000 | 150,100,000 | 154,400,000 | 134,700,000 | 108,100,000 |  | 488,300,000 | 547,300,000 | 366,000,000.0
Pre-tax income (loss) | $ 56,500,000 | $ 51,100,000 | $ 15,800,000 | $ 281,700,000 | $ (144,100,000) | $ 44,300,000 | $ (12,400,000) | $ (66,000,000.0) |  | 405,100,000 | (178,200,000) | 7,800,000
HG Global-BAM |  |  |  |  |  |  |  |  |  |  |  |
Segment reporting information |  |  |  |  |  |  |  |  |  |  |  |
Net investment income |  |  |  |  |  |  |  |  |  | 21,600,000 | 16,700,000 | 12,300,000
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  |  | (7,500,000) | 600,000
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  | 27,100,000 |  |
Commission revenues |  |  |  |  |  |  |  |  |  | 0 |  |
Other revenue |  |  |  |  |  |  |  |  |  | 1,600,000 | 1,200,000 | 1,000,000.0
Total revenues |  |  |  |  |  |  |  |  |  | 66,600,000 | 24,300,000 | 23,300,000
Insurance acquisition expense |  |  |  |  |  |  |  |  |  | 5,700,000 | 5,300,000 | 4,000,000.0
Other underwriting expenses |  |  |  |  |  |  |  |  |  | 400,000 | 400,000 | 400,000
Cost of sales |  |  |  |  |  |  |  |  |  | 0 |  |
General and administrative expenses |  |  |  |  |  |  |  |  |  | 50,500,000 | 48,000,000.0 | 42,900,000
Broker commission expense |  |  |  |  |  |  |  |  |  | 0 |  |
Amortization of other intangible assets |  |  |  |  |  |  |  |  |  | 0 |  |
Interest expense |  |  |  |  |  |  |  |  |  | 0 |  |
Total expenses |  |  |  |  |  |  |  |  |  | 56,600,000 | 53,700,000 | 47,300,000
Pre-tax income (loss) |  |  |  |  |  |  |  |  |  | 10,000,000.0 | (29,400,000) | (24,000,000.0)
NSM Holding Co LLC |  |  |  |  |  |  |  |  |  |  |  |
Segment reporting information |  |  |  |  |  |  |  |  |  |  |  |
Earned insurance premiums |  |  |  |  |  |  |  |  |  | 0 |  |
Net investment income |  |  |  |  |  |  |  |  |  | 0 |  |
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  | 0 |  |
Commission revenues |  |  |  |  |  |  |  |  |  | 193,400,000 | 89,600,000 | 0
Other revenue |  |  |  |  |  |  |  |  |  | 39,700,000 | 12,000,000.0 | 0
Total revenues |  |  |  |  |  |  |  |  |  | 233,100,000 | 101,600,000 | 0
Insurance acquisition expense |  |  |  |  |  |  |  |  |  | 0 |  |
Other underwriting expenses |  |  |  |  |  |  |  |  |  | 0 |  |
Change in fair value of contingent consideration earnout liabilities |  |  |  |  |  |  |  |  |  | 2,100,000 | 2,700,000 | 0
Cost of sales |  |  |  |  |  |  |  |  |  | 0 |  |
General and administrative expenses |  |  |  |  |  |  |  |  |  | 132,200,000 | 59,400,000 | 0
Broker commission expense |  |  |  |  |  |  |  |  |  | 64,800,000 | 28,400,000 | 0
Amortization of other intangible assets |  |  |  |  |  |  |  |  |  | 19,400,000 | 8,300,000 | 0
Interest expense |  |  |  |  |  |  |  |  |  | 16,700,000 | 8,000,000.0 | 0
Total expenses |  |  |  |  |  |  |  |  |  | 235,200,000 | 106,800,000 | 0
Pre-tax income (loss) |  |  |  |  |  |  |  |  |  | $ (2,100,000) | $ (5,200,000) |
Percentage of commission revenue |  |  |  |  |  |  |  |  |  | 17.00% | 33.00% |
Kudu |  |  |  |  |  |  |  |  |  |  |  |
Segment reporting information |  |  |  |  |  |  |  |  |  |  |  |
Earned insurance premiums |  |  |  |  |  |  |  |  |  | $ 0 |  |
Net investment income |  |  |  |  |  |  |  |  |  | 14,700,000 | $ 0 | 0
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  |  | 0 | 0
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  | 6,300,000 |  |
Commission revenues |  |  |  |  |  |  |  |  |  | 0 |  |
Other revenue |  |  |  |  |  |  |  |  |  | 200,000 | 0 | 0
Total revenues |  |  |  |  |  |  |  |  |  | 21,200,000 | 0 | 0
Insurance acquisition expense |  |  |  |  |  |  |  |  |  | 0 |  |
Other underwriting expenses |  |  |  |  |  |  |  |  |  | 0 |  |
Cost of sales |  |  |  |  |  |  |  |  |  | 0 |  |
General and administrative expenses |  |  |  |  |  |  |  |  |  | 10,100,000 | 0 | 0
Broker commission expense |  |  |  |  |  |  |  |  |  | 0 |  |
Amortization of other intangible assets |  |  |  |  |  |  |  |  |  | 200,000 | 0 | 0
Interest expense |  |  |  |  |  |  |  |  |  | 100,000 | 0 | 0
Total expenses |  |  |  |  |  |  |  |  |  | 10,400,000 | 0 | 0
Pre-tax income (loss) |  |  |  |  |  |  |  |  |  | 10,800,000 |  |
MediaAlpha |  |  |  |  |  |  |  |  |  |  |  |
Segment reporting information |  |  |  |  |  |  |  |  |  |  |  |
Commission revenues |  |  |  |  |  |  |  |  |  | 48,800,000 | 295,500,000 | 163,200,000
Other revenue |  |  |  |  |  |  |  |  |  | 0 | 1,600,000 | 0
Total revenues |  |  |  |  |  |  |  |  |  | 48,800,000 | 297,100,000 | 163,200,000
Cost of sales |  |  |  |  |  |  |  |  |  | 40,600,000 | 245,000,000.0 | 135,900,000
General and administrative expenses |  |  |  |  |  |  |  |  |  | 12,500,000 | 31,700,000 | 16,200,000
Amortization of other intangible assets |  |  |  |  |  |  |  |  |  | 1,600,000 | 10,300,000 | 10,500,000
Interest expense |  |  |  |  |  |  |  |  |  | 200,000 | 1,200,000 | 1,000,000.0
Total expenses |  |  |  |  |  |  |  |  |  | 54,900,000 | 288,200,000 | 163,600,000
Pre-tax income (loss) |  |  |  |  |  |  |  |  |  | (6,100,000) | $ 8,900,000 | $ (400,000)
Percentage of advertising revenue |  |  |  |  |  |  |  |  |  |  | 29.00% | 27.00%
Other |  |  |  |  |  |  |  |  |  |  |  |
Segment reporting information |  |  |  |  |  |  |  |  |  |  |  |
Earned insurance premiums |  |  |  |  |  |  |  |  |  | 0 | $ 0 | $ 1,000,000.0
Net investment income |  |  |  |  |  |  |  |  |  | 43,400,000 | 42,300,000 | 43,700,000
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  |  | (100,800,000) | 132,700,000
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  | 285,100,000 |  |
Realized gain and unrealized investment gain from the MediaAlpha Transaction |  |  |  |  |  |  |  |  |  |  | 0 | 0
Commission revenues |  |  |  |  |  |  |  |  |  | 6,900,000 | 4,100,000 | 3,800,000
Other revenue |  |  |  |  |  |  |  |  |  | 6,100,000 | 500,000 | 6,100,000
Total revenues |  |  |  |  |  |  |  |  |  | 523,700,000 | (53,900,000) | 187,300,000
Loss and loss adjustment expenses |  |  |  |  |  |  |  |  |  | 0 | 0 | 1,100,000
Insurance acquisition expense |  |  |  |  |  |  |  |  |  | 0 | 0 | 100,000
Other underwriting expenses |  |  |  |  |  |  |  |  |  | 0 |  |
Cost of sales |  |  |  |  |  |  |  |  |  | 7,500,000 | 3,700,000 | 3,500,000
General and administrative expenses |  |  |  |  |  |  |  |  |  | 122,500,000 | 94,400,000 | 148,900,000
Broker commission expense |  |  |  |  |  |  |  |  |  | 0 |  |
Amortization of other intangible assets |  |  |  |  |  |  |  |  |  | 600,000 | 200,000 | 200,000
Interest expense |  |  |  |  |  |  |  |  |  | 600,000 | 300,000 | 1,300,000
Total expenses |  |  |  |  |  |  |  |  |  | 131,200,000 | 98,600,000 | 155,100,000
Pre-tax income (loss) |  |  |  |  |  |  |  |  |  | 392,500,000 | $ (152,500,000) | $ 32,200,000
MediaAlpha |  |  |  |  |  |  |  |  |  |  |  |
Segment reporting information |  |  |  |  |  |  |  |  |  |  |  |
Gain from deconsolidation of MediaAlpha |  |  |  |  |  |  |  |  |  | 182,200,000 |  |
MediaAlpha | MediaAlpha |  |  |  |  |  |  |  |  |  |  |  |
Segment reporting information |  |  |  |  |  |  |  |  |  |  |  |
Total revenues |  |  |  |  |  |  |  |  | $ 359,200,000 |  |  |
MediaAlpha | Other |  |  |  |  |  |  |  |  |  |  |  |
Segment reporting information |  |  |  |  |  |  |  |  |  |  |  |
Realized gain and unrealized investment gain from the MediaAlpha Transaction |  |  |  |  |  |  |  |  |  | $ 182,200,000 |  |

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