Investments Available for Sale (Details 4)	3 Months Ended
	Mar. 31, 2016 USD ($) security	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Realized gross gains and losses on the sale of investments available for sale
Realized gross gains	$ 1,148,000	$ 788,000
Realized gross losses	670,000	139,000
Fair Value
Less than 12 months	188,828,000		$ 633,959,000
12 months or more	77,991,000		66,780,000
Total	266,819,000		700,739,000
Gross Unrealized Losses
Less than 12 months	(2,449,000)		(7,212,000)
12 months or more	(1,304,000)		(1,661,000)
Total	(3,753,000)		(8,873,000)
Other information
Other-than-temporary impairments	$ 7,000	$ 0
Number of securities in unrealized loss position that are intended to be sold | security	1
Fair value of investments deposited with insurance regulatory authorities	$ 8,600,000		8,500,000
U.S. Treasury securities
Fair Value
Less than 12 months	3,819,000		110,699,000
Total	3,819,000		110,699,000
Gross Unrealized Losses
Less than 12 months	(11,000)		(1,088,000)
Total	(11,000)		(1,088,000)
Municipal debt securities
Fair Value
Less than 12 months	21,414,000		47,850,000
12 months or more	4,616,000		1,254,000
Total	26,030,000		49,104,000
Gross Unrealized Losses
Less than 12 months	(140,000)		(255,000)
12 months or more	(50,000)		(7,000)
Total	(190,000)		(262,000)
Corporate debt securities
Fair Value
Less than 12 months	68,697,000		252,792,000
12 months or more	20,307,000		9,404,000
Total	89,004,000		262,196,000
Gross Unrealized Losses
Less than 12 months	(930,000)		(3,447,000)
12 months or more	(185,000)		(405,000)
Total	(1,115,000)		(3,852,000)
Mortgage-backed securities
Fair Value
Less than 12 months	9,984,000		23,360,000
12 months or more	23,319,000		26,075,000
Total	33,303,000		49,435,000
Gross Unrealized Losses
Less than 12 months	(282,000)		(458,000)
12 months or more	(476,000)		(663,000)
Total	(758,000)		(1,121,000)
Asset-backed securities
Fair Value
Less than 12 months	67,435,000		86,431,000
12 months or more	24,703,000		26,364,000
Total	92,138,000		112,795,000
Gross Unrealized Losses
Less than 12 months	(1,059,000)		(871,000)
12 months or more	(538,000)		(448,000)
Total	(1,597,000)		(1,319,000)
Essent Re
Other information
Fair value of the required investments on deposit in trusts	203,800,000		171,500,000
U.S. Agency | U.S. agency securities
Fair Value
Less than 12 months			11,362,000
Total			11,362,000
Gross Unrealized Losses
Less than 12 months			(178,000)
Total			(178,000)
U.S. Agency | Mortgage backed securities
Fair Value
Less than 12 months	17,479,000		101,465,000
12 months or more	5,046,000		3,683,000
Total	22,525,000		105,148,000
Gross Unrealized Losses
Less than 12 months	(27,000)		(915,000)
12 months or more	(55,000)		(138,000)
Total	$ (82,000)		$ (1,053,000)