Investments (Fixed Maturity and Equity Security Proceeds)(Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Available For Sale
Proceeds from sales(2)	$ 34,618	$ 5,760	$ 17,854
Fixed maturities, available-for-sale:
Available For Sale
Proceeds from sales(1)	833,562	171,589	245,618
Proceeds from maturities/repayments(1)	495,969	642,503	656,249
Gross investment gains from sales, prepayments and maturities	94,262	12,496	20,394
Gross investment losses from sales and maturities	(10,475)	(1,528)	(2,704)
Fixed maturity and equity security impairments:
Net writedowns for other-than-temporary impairment losses on fixed maturities recognized in earnings	(17,677)	(1,463)	(127)
Equity securities, available-for-sale:
Available For Sale
Gross investment gains from sales, prepayments and maturities	363	400	1,085
Gross investment losses from sales and maturities	(1,933)	0	0
Proceeds from sales(2)	34,618	5,732	17,873
Fixed maturity and equity security impairments:
Writedowns for impairments on equity securities	$ 0	$ (3)	$ 0