Income Taxes (Details 4) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits	$ 0	$ 0
Liability for uncertain tax positions	0	$ 0
U.S.
Operating Loss Carryforwards [Line Items]
Taxes provided on un-remitted earnings	0
Cumulative amount of earnings that would be subject to withholding tax, if distributed outside of the U.S.	846,800,000
Essent Irish Intermediate | Essent Holdings
Operating Loss Carryforwards [Line Items]
Withholding taxes accrued with respect to un-remitted earnings	0
United States Ireland Tax Treaty Benefits Availed | U.S.
Operating Loss Carryforwards [Line Items]
Associated withholding tax liability on cumulative amount of earnings that would be subject to withholding tax, if distributed outside of the U.S.	$ 42,300,000
United States Ireland Tax Treaty Benefits Availed | Essent Irish Intermediate | Essent Holdings
Operating Loss Carryforwards [Line Items]
Withholding tax rate on dividends paid (as a percent)	5.00%
Absent Benefits Of United States Ireland Tax Treaty | Essent Irish Intermediate | Essent Holdings
Operating Loss Carryforwards [Line Items]
Withholding tax rate on dividends paid (as a percent)	30.00%