Insurance Operations - Asbestos and Environmental Related Losses and Salvage and Subrogation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Gross
Balance at beginning of year	$ 14,262	$ 15,628
Incurred losses and loss adjustment expense	430	30
Payments for losses and loss adjustment expenses	1,882	1,396
Balance at end of year	12,810	14,262
Ceded
Balance at beginning of year	9,860	11,116
Incurred losses and loss adjustment expense	66	24
Payments for losses and loss adjustment expenses	1,564	1,280
Balance at end of year	8,362	9,860
Net
Balance at beginning of year	4,402	4,512
Incurred losses and loss adjustment expense	364	6
Payments for losses and loss adjustment expenses	318	116
Balance at end of year	4,448	4,402
Salvage and Subrogation
Estimated salvage and subrogation recoverable	27,500	27,400
Liability Related To Assumed Asbestos And Environmental Reserves On Retroactive Basis From Prior Members Of Pool [Member]
Net
Balance at beginning of year	8,700
Balance at end of year	$ 8,400	$ 8,700