Investments (Fair Value and Losses by Investment Category and Length of Time in a Loss Position) (Details) - Fixed maturities - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	$ 412,963	$ 211,240
Less than Twelve Months, Gross Unrealized Losses	18,748	3,131
Twelve Months or More, Fair Value	261,568	293,974
Twelve Months or More, Gross Unrealized Losses	31,191	20,712
Total, Fair Value	674,531	505,214
Total, Gross Unrealized Losses	49,939	23,843
Foreign government bonds
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	2,119	2,152
Less than Twelve Months, Gross Unrealized Losses	42	1
Twelve Months or More, Fair Value	0	400
Twelve Months or More, Gross Unrealized Losses	0	0
Total, Fair Value	2,119	2,552
Total, Gross Unrealized Losses	42	1
U.S. public corporate securities
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	119,249	81,622
Less than Twelve Months, Gross Unrealized Losses	6,812	984
Twelve Months or More, Fair Value	4,858	19,206
Twelve Months or More, Gross Unrealized Losses	1,164	1,263
Total, Fair Value	124,107	100,828
Total, Gross Unrealized Losses	7,976	2,247
U.S. private corporate securities
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	85,321	33,264
Less than Twelve Months, Gross Unrealized Losses	4,514	780
Twelve Months or More, Fair Value	3,772	22,143
Twelve Months or More, Gross Unrealized Losses	287	226
Total, Fair Value	89,093	55,407
Total, Gross Unrealized Losses	4,801	1,006
Foreign public corporate securities
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	10,640	3,839
Less than Twelve Months, Gross Unrealized Losses	819	23
Twelve Months or More, Fair Value	5,312	9,379
Twelve Months or More, Gross Unrealized Losses	1,943	362
Total, Fair Value	15,952	13,218
Total, Gross Unrealized Losses	2,762	385
Foreign private corporate securities
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	148,434	32,800
Less than Twelve Months, Gross Unrealized Losses	5,474	921
Twelve Months or More, Fair Value	192,258	186,693
Twelve Months or More, Gross Unrealized Losses	26,330	18,630
Total, Fair Value	340,692	219,493
Total, Gross Unrealized Losses	31,804	19,551
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	47,117	32,361
Less than Twelve Months, Gross Unrealized Losses	1,087	243
Twelve Months or More, Fair Value	55,368	55,461
Twelve Months or More, Gross Unrealized Losses	1,467	223
Total, Fair Value	102,485	87,822
Total, Gross Unrealized Losses	2,554	466
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	22,153
Less than Twelve Months, Gross Unrealized Losses	0	163
Twelve Months or More, Fair Value	0	0
Twelve Months or More, Gross Unrealized Losses	0	0
Total, Fair Value	0	22,153
Total, Gross Unrealized Losses	0	163
Residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	83	3,049
Less than Twelve Months, Gross Unrealized Losses	0	16
Twelve Months or More, Fair Value	0	692
Twelve Months or More, Gross Unrealized Losses	0	8
Total, Fair Value	83	3,741
Total, Gross Unrealized Losses	$ 0	$ 24