Investments (Investment Gains and Losses) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Gross Unrealized Gains and Losses [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 1,325,717	$ 1,321,487
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	144,317	169,806
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	2,267	1,910
Debt Securities, Available-for-sale	1,467,767	1,489,383
US Treasury Securities [Member]
Gross Unrealized Gains and Losses [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	9,559	9,529
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,425	1,797
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-sale	10,984	11,326
US Government Agencies Debt Securities [Member]
Gross Unrealized Gains and Losses [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	3,477	3,490
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,103	1,301
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-sale	4,580	4,791
US States and Political Subdivisions Debt Securities [Member]
Gross Unrealized Gains and Losses [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	357,466	377,462
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	30,761	32,751
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	257	548
Debt Securities, Available-for-sale	387,970	409,665
Corporate Debt Securities Financial Sector Member [Domain]
Gross Unrealized Gains and Losses [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	206,393	204,160
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	23,908	31,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	180	13
Debt Securities, Available-for-sale	230,121	235,147
Corporate Debt Security Consumer Sector
Gross Unrealized Gains and Losses [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	210,132	196,648
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	25,239	30,116
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	620	245
Debt Securities, Available-for-sale	234,751	226,519
Corporate Debt Security Energy Sector
Gross Unrealized Gains and Losses [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	79,322	81,223
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	8,719	8,174
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	245	536
Debt Securities, Available-for-sale	87,796	88,861
Corporate Debt Security All Other Sector
Gross Unrealized Gains and Losses [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	297,277	284,209
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	34,196	42,554
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	959	82
Debt Securities, Available-for-sale	330,514	326,681
Commercial Mortgage Backed Securities [Member]
Gross Unrealized Gains and Losses [Line Items]
Debt Securities, Available-for-sale, Amortized Cost		225
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax		4
Debt Securities, Available-for-sale		221
Residential Mortgage Backed Securities [Member]
Gross Unrealized Gains and Losses [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	118,147	118,144
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	18,483	21,819
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-sale	136,630	139,963
Asset-backed Securities [Member]
Gross Unrealized Gains and Losses [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	43,843	46,295
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	470	278
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	6	482
Debt Securities, Available-for-sale	44,307	46,091
Foreign Government, Non-US [Member]
Gross Unrealized Gains and Losses [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	101	102
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	13	16
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-sale	$ 114	$ 118