Securities in an Unrealized Loss Position (Non-Investment Grade Fixed Maturity Securities) (Details) - External Credit Rating, Non Investment Grade $ in Thousands	Dec. 31, 2018 USD ($)
Foreign government
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	13
Aggregate Fair Value	$ 140,854
Gross Unrealized Loss	$ 21,411
Total corporate
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	13
Aggregate Fair Value	$ 120,078
Gross Unrealized Loss	$ 13,111
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	5
Aggregate Fair Value	$ 8,741
Gross Unrealized Loss	$ 69
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	5
Aggregate Fair Value	$ 14,662
Gross Unrealized Loss	$ 2,593
Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	36
Aggregate Fair Value	$ 284,335
Gross Unrealized Loss	$ 37,184