Related Party Transactions - ACAC (Details) (USD $)	9 Months Ended		18 Months Ended				1 Months Ended		1 Months Ended	0 Months Ended		31 Months Ended	3 Months Ended		6 Months Ended	9 Months Ended	0 Months Ended	3 Months Ended	33 Months Ended	9 Months Ended	3 Months Ended		6 Months Ended	9 Months Ended	3 Months Ended		6 Months Ended	9 Months Ended	0 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2012 Senior notes [Member] 8.25% Senior note [Member]	Dec. 31, 2011 Senior notes [Member] 8.25% Senior note [Member]	Jun. 30, 2011 Senior notes [Member] 8.25% Senior note [Member]	Jun. 30, 2011 Junior subordinated debt [Member] Trust Preferred Securities [Member]	Sep. 30, 2012 Junior subordinated debt [Member] Trust Preferred Securities [Member]	Jun. 30, 2011 American Capital Acquisition Corp. [Member] Senior notes [Member] 8.25% Senior note [Member]	Jul. 15, 2011 American Capital Acquisition Corp. [Member] Junior subordinated debt [Member] Trust Preferred Securities [Member] Maiden Capital Financing Trust [Member]	Sep. 30, 2012 American Capital Acquisition Corp. [Member] Junior subordinated debt [Member] Trust Preferred Securities [Member] Maiden Capital Financing Trust [Member]	Sep. 30, 2012 American Capital Acquisition Corp. [Member] ACAC Quota Share Reinsurance Agreement [Member]	Sep. 30, 2012 American Capital Acquisition Corp. [Member] ACAC Quota Share Reinsurance Agreement [Member] Commissions Paid [Member]	Jun. 30, 2011 American Capital Acquisition Corp. [Member] ACAC Quota Share Reinsurance Agreement [Member] Commissions Paid [Member]	Jun. 30, 2011 American Capital Acquisition Corp. [Member] ACAC Quota Share Reinsurance Agreement [Member] Commissions Paid [Member]	Sep. 30, 2012 American Capital Acquisition Corp. [Member] ACAC Quota Share Reinsurance Agreement [Member] Commissions Paid [Member]	Sep. 12, 2012 American Capital Acquisition Corp. [Member] ACAC Integon Consulting Agreement [Member]	Sep. 30, 2012 American Capital Acquisition Corp. [Member] ACAC Integon Consulting Agreement [Member]	Sep. 30, 2012 American Capital Acquisition Corp. [Member] ACAC Integon Consulting Agreement [Member]	Sep. 30, 2012 American Capital Acquisition Corp. [Member] ACAC New South Insurance Company Reinsurance Agreement [Member]	Sep. 30, 2012 American Capital Acquisition Corp. [Member] ACAC New South Insurance Company Reinsurance Agreement [Member] Commissions Paid [Member]	Jun. 30, 2011 American Capital Acquisition Corp. [Member] ACAC New South Insurance Company Reinsurance Agreement [Member] Commissions Paid [Member]	Jun. 30, 2011 American Capital Acquisition Corp. [Member] ACAC New South Insurance Company Reinsurance Agreement [Member] Commissions Paid [Member]	Sep. 30, 2012 American Capital Acquisition Corp. [Member] ACAC New South Insurance Company Reinsurance Agreement [Member] Commissions Paid [Member]	Sep. 30, 2012 American Capital Acquisition Corp. [Member] ACAC New South Insurance Company Reinsurance Agreement [Member] Premiums Earned [Member]	Jun. 30, 2011 American Capital Acquisition Corp. [Member] ACAC New South Insurance Company Reinsurance Agreement [Member] Premiums Earned [Member]	Jun. 30, 2011 American Capital Acquisition Corp. [Member] ACAC New South Insurance Company Reinsurance Agreement [Member] Premiums Earned [Member]	Sep. 30, 2012 American Capital Acquisition Corp. [Member] ACAC New South Insurance Company Reinsurance Agreement [Member] Premiums Earned [Member]	Jul. 15, 2011 American Capital Acquisition Corp. [Member] AmTrust International Insurance, Ltd. [Member] Junior subordinated debt [Member] Trust Preferred Securities [Member] Maiden Capital Financing Trust [Member]	Jul. 15, 2011 Michael Karfunkel [Member] Junior subordinated debt [Member] Trust Preferred Securities [Member] Maiden Capital Financing Trust [Member]	Jul. 15, 2011 George Karfunkel [Member] Junior subordinated debt [Member] Trust Preferred Securities [Member] Maiden Capital Financing Trust [Member]
Related Party Transaction [Line Items]
Percent of net premiums of personal lines business reinsured												25.00%
Percent participation in quota share by parent												50.00%
Percent of net premiums of personal lines business received by parent												25.00%
Percent of net premiums of personal lines business received by reinsurers												50.00%
Percent of net losses related to premiums of personal lines business assumed by reinsurers												50.00%
Agreement period												3 years					1 year
Contract extension												3 years					1 year
Cancellation notice period			4 months									9 months					120 days
Cancellation notice period upon the occurrence of certain early termination events												60 days
Early termination events, reduction threshold of stockholders' equity												50.00%
Cancellation notice period upon the occurrence of IPO												9 months
Commission rate, percent of ceded written premiums												32.50%
Commission rate, adjusted percent of ceded written premiums												34.50%
Commission rate, adjustment criteria, loss ratio ceiling												60.50%
Commission rate, reduced adjustment to percent of ceded written premiums												30.50%
Commission rate, adjustment criteria, loss ratio floor												64.50%
Expenses recorded from related party transactions													$ 21,856,000	$ 19,156,000	$ 55,458,000	$ 63,435,000					$ 0	$ 0	$ 200	$ 0
Monthly base fee																	25,000
Fee rate per policy quote																	100
Fee rate per policy requote																	100
Face amount				107,500,000	107,500,000				107,500,000		260,000,000
Percent of personal lines business ceded to related party																				100.00%
Revenue from related parties																		0	0						0	0	(600)	0
Stated interest rate						8.25%		14.00%	8.25%
Principal amount repurchased	$ 0	$ 107,500,000					$ 107,500,000		$ 107,500,000	$ 12,500,000																			$ 12,500,000	$ 79,066,000	$ 25,000,000