Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Common Stock Outstanding and Additional Paid-In Capital [Roll Forward]
Dividends paid to shareholders	$ 5,857		$ 16,835	$ 16,302
Cash dividends paid (in dollars per share)	$ 0.40		$ 1.12	$ 1.08
Stock repurchase program, shares authorized (in shares)	2,464,209
Stock repurchase program, authorized amount	$ 25,000
Stock repurchase program, authorized amount per quarter	6,250
Repurchase of common shares	11,501		$ 4,596	$ 1,880
Investments [Abstract]
Total unrealized gain (loss) before federal income tax expense (benefit)	12,491		(7,859)
Deferred tax benefit (liability)	(2,628)		1,651
Net unrealized gains (losses) on investments	9,863		(6,208)
Foreign exchange adjustment [Abstract]
Total unrealized losses	(625)		(1,442)
Deferred tax benefit	131		303
Net unrealized losses on foreign exchange adjustment	(494)		(1,139)
Accumulated other comprehensive income (loss)	9,369		(7,347)
Investments [Abstract]
Pre-tax holding gains (losses) on fixed income securities arising during period	19,182	[1]	(12,253)	26,677
Less: applicable federal income tax expense (benefit)	4,028		(2,573)	9,337
Net unrealized gains (losses) on investments	15,154		(9,680)	17,340
Pre-tax gains (losses) on fixed income securities included in net income (loss) during period	(1,161)	[1]	(3,560)	7,217
Less: applicable federal income tax expense (benefit)	(244)		(748)	2,526
Other comprehensive income (loss), reclassification adjustment for sale of securities included in net income, net of tax	(917)		(2,812)	4,691
Change in unrealized gains (losses) on investments	$ 16,071		$ (6,868)	$ 12,649
Class A [Member]
Increase (Decrease) in Common Stock Outstanding and Additional Paid-In Capital [Roll Forward]
Stated value of common stock (in dollars per share)	$ 0.04
Repurchase of common stock (in shares)	11,989
Average share price (in dollars per share)	$ 15.70
Class B [Member]
Increase (Decrease) in Common Stock Outstanding and Additional Paid-In Capital [Roll Forward]
Stated value of common stock (in dollars per share)	$ 0.04
Repurchase of common stock (in shares)	665,099
Average share price (in dollars per share)	$ 17.01
Rule 10b5-1 [Member]
Increase (Decrease) in Common Stock Outstanding and Additional Paid-In Capital [Roll Forward]
Stock repurchase program, authorized amount	$ 625

[1] Effective January 1, 2018, the Company adopted ASU 2016-01 and unrealized gains (losses) related to equity securities are no longer reflected in accumulated other comprehensive income (loss). Prior periods have not been restated to conform to the current presentation.