Schedule II Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Income Statements, Captions [Line Items]
Net investment income									$ 17,812	$ 10,679	$ 9,212
Total revenue									654,420	487,117	357,569
Operating Expenses									27,675	20,524	15,316
General and Administrative Expense									81,762	42,956	29,852
Interest Expense									3,247	723	326
Total expenses									653,663	480,214	316,003
Operating Income (Loss)									757	6,903	41,566
Other Nonoperating Income (Expense)									153	100	294
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest									(910)	(7,003)	(41,860)
Income Tax Expense (Benefit)									(9,235)	1,305	14,502
Net income	$ 27,001	$ (28,012)	$ 7,257	$ 3,899	$ (10,517)	$ 3,423	$ 9,841	$ 2,951	10,145	5,698	27,358
Change in net unrealized gain (loss) on investments									10,647	(629)	(3,070)
Reclassification adjustment for net realized investment gains									(67)	(547)	(827)
Income tax benefit (expense) related to items of other comprehensive income									(2,181)	378	1,506
Total comprehensive income									18,544	4,900	24,967
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Income (Loss) from Subsidiaries, Net of Tax									14,000	13,296	27,562
Realized Investment Gains (Losses)									0	(14)	951
Net investment income									53	88	239
Total revenue									14,053	13,370	28,752
Operating Expenses									348	337	138
General and Administrative Expense									9,078	11,805	1,252
Interest Expense									2,939	496	0
Total expenses									12,365	12,638	1,390
Operating Income (Loss)									1,688	732	27,362
Other Nonoperating Income (Expense)									75	60	245
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest									(1,763)	(792)	(27,607)
Income Tax Expense (Benefit)									(8,382)	(4,906)	249
Net income									10,145	5,698	27,358
Change in net unrealized gain (loss) on investments									10,647	(629)	(3,070)
Reclassification adjustment for net realized investment gains									(67)	(547)	(827)
Income tax benefit (expense) related to items of other comprehensive income									(2,181)	378	1,506
Total comprehensive income									$ 18,544	$ 4,900	$ 24,967