Related Party Transactions - Narrative and AmTrust (Details) $ in Thousands												1 Months Ended		3 Months Ended		6 Months Ended
	Jan. 24, 2019	Jan. 11, 2019 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jul. 01, 2018	Jan. 01, 2018	Jul. 01, 2016	Jan. 01, 2012 EUR (€)	Apr. 01, 2011 EUR (€)	Jun. 11, 2008	Jul. 01, 2007	Jan. 31, 2019 USD ($)	Jan. 31, 2019 EUR (€)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Dec. 18, 2017
Related Party Transaction [Line Items]
Loan to related party				$ 167,975										$ 167,975		$ 167,975
Leah Karfunkel
Related Party Transaction [Line Items]
Noncontrolling interest, ownership percentage														8.00%		8.00%
Leah Karfunkel | National General Holdings Corp.
Related Party Transaction [Line Items]
Noncontrolling interest, ownership percentage														39.40%		39.40%
Barry Zyskind
Related Party Transaction [Line Items]
Noncontrolling interest, ownership percentage														7.50%		7.50%
George Karfunkel, less than 5% ownership
Related Party Transaction [Line Items]
Noncontrolling interest, ownership percentage														5.00%		5.00%
Founding shareholders | AmTrust Financial Services, Inc.
Related Party Transaction [Line Items]
Controlling interest, ownership percentage														53.60%		53.60%
AmTrust Financial Services, Inc. | London Interbank Offered Rate (LIBOR)
Related Party Transaction [Line Items]
Basis spread on variable rate																		2.00%
AmTrust Financial Services, Inc. | AmTrust Quota Share Reinsurance Agreement
Related Party Transaction [Line Items]
Percent of premiums written, net of cost of unaffiliated inuring reinsurance from related party											40.00%
Percent of losses with respect to current lines of business, excluding those above covered business threshold to related party					40.00%						40.00%
Commission rate, percent of ceded written premiums										34.375%	31.00%
AmTrust Financial Services, Inc. | AmTrust Quota Share Reinsurance Agreement | Returned Gross Unearned Premiums
Related Party Transaction [Line Items]
Related party transaction amount			$ (647,980)
AmTrust Financial Services, Inc. | AmTrust Quota Share Reinsurance Agreement | Returned Gross Unearned Premiums | AmTrust International Insurance, Ltd. (AII)
Related Party Transaction [Line Items]
Related party transaction amount														$ 43,240
AmTrust Financial Services, Inc. | AmTrust Quota Share Reinsurance Agreement | Returned Unearned Premiums, Net
Related Party Transaction [Line Items]
Related party transaction amount												$ (436,760)
AmTrust Financial Services, Inc. | AmTrust Quota Share Reinsurance Agreement | Cash And Investments Transferred Due To Unearned Premiums
Related Party Transaction [Line Items]
Related party transaction amount												(480,000)
AmTrust Financial Services, Inc. | AmTrust Quota Share Reinsurance Agreement | Funds Withheld Arrangement
Related Party Transaction [Line Items]
Related party transaction amount		$ (575,000)														$ 575,000
Interest income from related party														5,017		9,443
Accrued interest on collateral held by related party														5,017		5,017
Interest rate		3.50%
AmTrust Financial Services, Inc. | AmTrust Quota Share Reinsurance Agreement | AmTrust Quota Shares Reinsurance Agreement, Partial Termination Amendment
Related Party Transaction [Line Items]
Percent of ceding commission payable, period increase				5.00%
AmTrust Financial Services, Inc. | AmTrust Quota Share Reinsurance Agreement | Minimum
Related Party Transaction [Line Items]
Commission rate, adjustment criteria, loss ratio floor					81.50%
AmTrust Financial Services, Inc. | AmTrust Quota Share Reinsurance Agreement | Maximum
Related Party Transaction [Line Items]
Commission rate, adjustment criteria, loss ratio ceiling					95.00%
AmTrust Financial Services, Inc. | European Hospital Liability Quota Share Agreement
Related Party Transaction [Line Items]
Commission rate, percent of ceded written premiums									5.00%
Premiums and losses related to policies, percentage							32.50%		40.00%
Maximum limit of liability attaching (in EUR) | €								€ 10,000,000	€ 5,000,000
Percent basis currency equivalent of maximum limit of liability attaching									100.00%
Future premiums and losses related to policies, percentage							20.00%
AmTrust Financial Services, Inc. | Reinsurer Trust Assets Collateral Agreement
Related Party Transaction [Line Items]
Collateral held by related party				$ 3,650,418										2,521,158		2,521,158
Accrued interest on collateral held by related party				23,283										13,203		13,203
AmTrust Financial Services, Inc. | Reinsurance Brokerage Agreements
Related Party Transaction [Line Items]
Brokerage fee, percent of premium assumed											1.25%
Cancellation notice period											30 days
AmTrust Financial Services, Inc. | Reinsurance Brokerage Agreements | Brokerage expense
Related Party Transaction [Line Items]
Expenses recorded from related party transactions														1,398	$ 5,966	3,375	$ 12,263
Balances due to related party				14,199										3,502		3,502
AmTrust Financial Services, Inc. | Asset Management Agreement
Related Party Transaction [Line Items]
Cancellation notice period											30 days
Quarterly brokerage fee, above portfolio threshold, percent of average holdings						0.02125%					0.0375%
AmTrust Financial Services, Inc. | Asset Management Agreement | Investment Management Fee
Related Party Transaction [Line Items]
Expenses recorded from related party transactions														$ 678	$ 1,033	$ 1,453	$ 2,082
AmTrust Financial Services, Inc. | National General Holdings Corp.
Related Party Transaction [Line Items]
Noncontrolling interest, ownership percentage														1.50%		1.50%
AEL | AmTrust Quota Share Reinsurance Agreement
Related Party Transaction [Line Items]
Percentage ceded					20.00%
AEL | AmTrust European Hospital Liability Quota Share Agreement
Related Party Transaction [Line Items]
Collateral held by related party				249,948										$ 248,878		$ 248,878
Accrued interest on collateral held by related party				$ 1,976										2,022		2,022
AmTrust International Underwriters DAC (AIU) | AmTrust European Hospital Liability Quota Share Agreement | Collateral Provided For Share Under Quota Share Agreement
Related Party Transaction [Line Items]
Related party transaction amount												$ (51,244)	€ (45,113,000)			58,123
Interest income from related party														$ 72		125
Interest rate	0.50%
AmTrust International Underwriters DAC (AIU) | AmTrust European Hospital Liability Quota Share Agreement | Accrued Interest On Collateral Provided For Share Under Quota Share Agreement
Related Party Transaction [Line Items]
Related party transaction amount																$ 127