Reinsurance - Excess of Loss Reinsurance (Details) - Mortgage Insurance	12 Months Ended
	Dec. 31, 2020
Essent Guaranty | Radnor Re | Variable Interest Entity
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Amortization period	10 years
Essent Guaranty | Other Reinsurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Amortization period	10 years
Radnor Re | Variable Interest Entity | Mortgage Insurance Linked Notes
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance debt issued to cover insurance term	10 years