Investments Available for Sale (Details 4)	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) security	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Realized gross gains and losses on the sale of investments available for sale
Realized gross gains	$ 624,000	$ 1,339,000	$ 1,772,000	$ 2,127,000
Realized gross losses	41,000	$ 771,000	711,000	910,000
Fair Value
Less than 12 months	82,067,000		82,067,000		$ 633,959,000
12 months or more	93,203,000		93,203,000		66,780,000
Total	175,270,000		175,270,000		700,739,000
Gross Unrealized Losses
Less than 12 months	(565,000)		(565,000)		(7,212,000)
12 months or more	(1,358,000)		(1,358,000)		(1,661,000)
Total	$ (1,923,000)		(1,923,000)		(8,873,000)
Other information
Other-than-temporary impairments			7,000	$ 0
Number of securities sold previously in unrealized loss positions | security	1
Fair value of investments deposited with insurance regulatory authorities	$ 8,600,000		8,600,000		8,500,000
U.S. Treasury securities
Fair Value
Less than 12 months	1,726,000		1,726,000		110,699,000
12 months or more	0		0		0
Total	1,726,000		1,726,000		110,699,000
Gross Unrealized Losses
Less than 12 months	(1,000)		(1,000)		(1,088,000)
12 months or more	0		0		0
Total	(1,000)		(1,000)		(1,088,000)
Municipal debt securities
Fair Value
Less than 12 months	6,409,000		6,409,000		47,850,000
12 months or more	6,512,000		6,512,000		1,254,000
Total	12,921,000		12,921,000		49,104,000
Gross Unrealized Losses
Less than 12 months	(20,000)		(20,000)		(255,000)
12 months or more	(29,000)		(29,000)		(7,000)
Total	(49,000)		(49,000)		(262,000)
Corporate debt securities
Fair Value
Less than 12 months	16,708,000		16,708,000		252,792,000
12 months or more	21,960,000		21,960,000		9,404,000
Total	38,668,000		38,668,000		262,196,000
Gross Unrealized Losses
Less than 12 months	(88,000)		(88,000)		(3,447,000)
12 months or more	(197,000)		(197,000)		(405,000)
Total	(285,000)		(285,000)		(3,852,000)
Mortgage-backed securities
Fair Value
Less than 12 months	6,178,000		6,178,000		23,360,000
12 months or more	20,642,000		20,642,000		26,075,000
Total	26,820,000		26,820,000		49,435,000
Gross Unrealized Losses
Less than 12 months	(71,000)		(71,000)		(458,000)
12 months or more	(408,000)		(408,000)		(663,000)
Total	(479,000)		(479,000)		(1,121,000)
Asset-backed securities
Fair Value
Less than 12 months	50,049,000		50,049,000		86,431,000
12 months or more	38,612,000		38,612,000		26,364,000
Total	88,661,000		88,661,000		112,795,000
Gross Unrealized Losses
Less than 12 months	(379,000)		(379,000)		(871,000)
12 months or more	(704,000)		(704,000)		(448,000)
Total	(1,083,000)		(1,083,000)		(1,319,000)
Essent Re
Other information
Fair value of the required investments on deposit in trusts	272,900,000		272,900,000		171,500,000
U.S. Agency | U.S. agency securities
Fair Value
Less than 12 months					11,362,000
12 months or more					0
Total					11,362,000
Gross Unrealized Losses
Less than 12 months					(178,000)
12 months or more					0
Total					(178,000)
U.S. Agency | Mortgage backed securities
Fair Value
Less than 12 months	997,000		997,000		101,465,000
12 months or more	5,477,000		5,477,000		3,683,000
Total	6,474,000		6,474,000		105,148,000
Gross Unrealized Losses
Less than 12 months	(6,000)		(6,000)		(915,000)
12 months or more	(20,000)		(20,000)		(138,000)
Total	$ (26,000)		$ (26,000)		$ (1,053,000)