Policy and Claim Reserves (Property and Casualty Reserve) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less reinsurance recoverable on unpaid losses	$ 771		$ 366
Net losses:
Estimated claims and claim adjustment expenses for claims arising in prior years	(1,097)	$ (751)
Consolidated Property and Casualty Insurance Entity
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance, beginning of year	6,927	7,812	7,075	$ 7,531
Less reinsurance recoverable on unpaid losses	185	526	327	1,184
Net balances at beginning of year	6,742	7,286	$ 6,748	$ 6,347
Net losses:
Provision for claims and claim adjustment expenses for claims arising in current year	9,185	10,786
Estimated claims and claim adjustment expenses for claims arising in prior years	(1,097)	(751)
Total increases	8,088	10,035
Claims and claim adjustment expense payments for claims arising in:
Current year	5,527	7,090
Prior years	2,567	2,006
Total payments	$ 8,094	$ 9,096