Investment Operations Realized gains losses on investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Gain (Loss) on Investments [Line Items]
Proceeds from Sale of Available-for-sale Securities, Debt	$ 109,500	$ 108,500	$ 67,200
Gain (Loss) on Short-term Investments, Cash and Cash Equivalents	(1)	0	0
Gain (Loss) on Investments, Excluding Other than Temporary Impairments	3,106	11,062	3,760
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	(4,869)	(573)	(822)
Gain (Loss) on Investments	(1,763)	10,489	2,938
Categories of Investments, Cost-method Investments [Member]
Gain (Loss) on Investments [Line Items]
Gain (Loss) on Sales of Loans, Net	817	0	0
Gain (Loss) on Disposition of Other Assets	491	8,233	0
Debt Securities [Member] | Categories of Investments, Marketable Securities, Available-for-sale Securities [Member]
Gain (Loss) on Investments [Line Items]
Gross gains - Available-for-sale Securities	9,793	4,781	4,593
Gross losses - Available-for-sale Securities	(8,523)	(1,952)	(833)
Equity Securities [Member] | Categories of Investments, Marketable Securities, Available-for-sale Securities [Member]
Gain (Loss) on Investments [Line Items]
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	529	0	0
Credit related portion of fixed maturity losses [Member]
Gain (Loss) on Investments [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	(4,767)	(363)	0
Other credit related impairments [Member]
Gain (Loss) on Investments [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	$ (102)	$ (210)	$ (822)