Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings [Member]
Balance, beginning of period at Dec. 31, 2019		$ 412		$ 1,593,281	$ 58,798
Cumulative effect from the adoption of new accounting standards, net at Dec. 31, 2019						$ (1,240)
Repurchases of common stock		(9)	$ (13,490)	(82,177)
Share-based compensation			13,492
Net issuance of common stock		2	(2)
Net income	$ 72,469			72,469
Dividends				(16,530)
Change in foreign currency translation adjustment,net of income taxes					(29,011)
Change in net unrealized investment gains (losses) during the period, net of income taxes					(65,881)
Balance, end of period at Mar. 31, 2020	$ 1,530,114	405		1,565,803	(36,094)
Dividends declared per share	$ 0.40
Balance, beginning of period at Dec. 31, 2020	$ 1,835,885	393		1,705,786	129,706
Cumulative effect from the adoption of new accounting standards, net at Dec. 31, 2020	1,705,786
Repurchases of common stock			(5,966)
Share-based compensation			14,105
Net issuance of common stock		1	(1)
Net income	97,872			97,872
Dividends				(18,620)
Change in foreign currency translation adjustment,net of income taxes					4,992
Change in net unrealized investment gains (losses) during the period, net of income taxes					(51,075)
Balance, end of period at Mar. 31, 2021	$ 1,877,193	$ 394	$ 8,138	$ 1,785,038	$ 83,623
Dividends declared per share	$ 0.47