Investments (Details 4) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) security	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) security	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) security
Investments, Debt and Equity Securities [Abstract]
Realized gross gains	$ 1,263	$ 1,923	$ 4,525	$ 2,594
Realized gross losses	2,103	1,225	2,230	1,236
Fair Value
Less than 12 months	342,581		342,581		$ 372,179
12 months or more	86,517		86,517		310,585
Total	429,098		429,098		682,764
Gross Unrealized Losses
Less than 12 months	(6,393)		(6,393)		(3,369)
12 months or more	(3,382)		(3,382)		(2,700)
Total	$ (9,775)		$ (9,775)		$ (6,069)
Other Information
Number of investment securities in an unrealized loss position | security	274		274		365
Other-than-temporary impairments	$ 400	$ 100	$ 400	$ 100
Other invested assets	78,536		78,536		$ 78,873
Fair value of investments deposited with insurance regulatory authorities	9,900		9,900		9,400
U.S. Treasury securities
Fair Value
Less than 12 months	15,983		15,983		29,013
12 months or more	0		0		42,981
Total	15,983		15,983		71,994
Gross Unrealized Losses
Less than 12 months	(1)		(1)		(331)
12 months or more	0		0		(76)
Total	(1)		(1)		(407)
U.S. agency securities
Fair Value
Less than 12 months					0
12 months or more					25,605
Total					25,605
Gross Unrealized Losses
Less than 12 months					0
12 months or more					(51)
Total					(51)
U.S. agency mortgage-backed securities
Fair Value
Less than 12 months	5,057		5,057		101,684
12 months or more	1,677		1,677		113,866
Total	6,734		6,734		215,550
Gross Unrealized Losses
Less than 12 months	(30)		(30)		(1,042)
12 months or more	(36)		(36)		(1,290)
Total	(66)		(66)		(2,332)
Municipal debt securities
Fair Value
Less than 12 months	32,488		32,488		10,651
12 months or more	0		0		624
Total	32,488		32,488		11,275
Gross Unrealized Losses
Less than 12 months	(391)		(391)		(112)
12 months or more	0		0		(6)
Total	(391)		(391)		(118)
Non-U.S. government securities:
Fair Value
Less than 12 months	3,903		3,903		9,664
12 months or more	0		0		0
Total	3,903		3,903		9,664
Gross Unrealized Losses
Less than 12 months	(142)		(142)		(47)
12 months or more	0		0		0
Total	(142)		(142)		(47)
Corporate debt securities
Fair Value
Less than 12 months	14,953		14,953		83,013
12 months or more	0		0		14,531
Total	14,953		14,953		97,544
Gross Unrealized Losses
Less than 12 months	(829)		(829)		(576)
12 months or more	0		0		(16)
Total	(829)		(829)		(592)
Residential and commercial mortgage securities
Fair Value
Less than 12 months	50,165		50,165		59,341
12 months or more	10,535		10,535		3,442
Total	60,700		60,700		62,783
Gross Unrealized Losses
Less than 12 months	(2,016)		(2,016)		(1,059)
12 months or more	(664)		(664)		(42)
Total	(2,680)		(2,680)		(1,101)
Asset-backed securities
Fair Value
Less than 12 months	155,022		155,022		78,813
12 months or more	74,305		74,305		109,536
Total	229,327		229,327		188,349
Gross Unrealized Losses
Less than 12 months	(2,974)		(2,974)		(202)
12 months or more	(2,682)		(2,682)		(1,219)
Total	(5,656)		(5,656)		(1,421)
Money market funds
Fair Value
Less than 12 months	65,010		65,010
12 months or more	0		0
Total	65,010		65,010
Gross Unrealized Losses
Less than 12 months	(10)		(10)
12 months or more	0		0
Total	(10)		(10)
Essent Re
Other Information
Fair value of the required investments on deposit in trusts	979,800		979,800		805,500
Essent Guaranty
Other Information
Assets on deposit under reinsurance agreement	8,500		8,500		6,400
Assets on deposit for the benefit of the sponsor	$ 12,000		$ 12,000		$ 6,400
Internal Investment Grade | Credit Concentration Risk | Securities
Other Information
Concentration risk, percentage			98.00%