Investments (Allowance for Losses) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for credit losses, beginning of year	$ 4,154	$ 8,904
Addition to (release of) allowance for losses	(355)	(1,832)
Charge-offs, net of recoveries	0	(2,918)
Total ending balance	3,799	4,154
Agricultural loans
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for credit losses, beginning of year	100
Total ending balance	$ 100	$ 100