Schedule II - Condensed Financial Information of Registrant - Supplementary Notes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Information of Registrant
Dividends paid to parent company	$ 0	$ 55,000,000.0	$ 0
Essent Guaranty
Condensed Financial Information of Registrant
Unassigned surplus	343,600,000
Dividends paid to parent company	0	0	40,000,000
Essent PA
Condensed Financial Information of Registrant
Unassigned surplus	15,400,000
Dividends paid to parent company	$ 0	$ 0	$ 0