Schedule II - Condensed Financial Information of Registrant, Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 100,408	$ 75,089	$ 81,747	$ 50,752
Deferred income tax asset, net	3,374	7,176
Income taxes receivable		800
Other assets	23,922	3,601
Total assets	1,090,550	773,063
Liabilities:
Accounts payable and accrued expenses	12,366	7,090
Income taxes payable	400
Other liabilities	977	20
Total liabilities	684,670	509,077
Stockholders' Equity [Abstract]
Common stock	222	212
Additional paid-in capital	229,229	158,485
Retained earnings	162,911	106,545
Accumulated other comprehensive income (loss)	13,518	(1,256)
Stockholders' equity	405,880	263,986	238,189	210,214
Total liabilities and stockholders' equity	1,090,550	773,063
Parent Company [Member]
Assets
Cash and cash equivalents	14,726	10,016	$ 1,502	$ 1,868
Due from subsidiaries	16,836	1,001
Investment in subsidiaries	391,071	251,591
Deferred income tax asset, net	519	369
Income taxes receivable	0	787
Other assets	208	549
Total assets	423,360	264,313
Liabilities:
Accounts payable and accrued expenses	260	308
Income taxes payable	434	0
Credit facility	16,744	0
Other liabilities	42	19
Total liabilities	17,480	327
Stockholders' Equity [Abstract]
Common stock	222	212
Additional paid-in capital	229,229	158,485
Retained earnings	162,911	106,545
Accumulated other comprehensive income (loss)	13,518	(1,256)
Stockholders' equity	405,880	263,986
Total liabilities and stockholders' equity	$ 423,360	$ 264,313