Fair Value Measurements (Quantitative Information Used As Level 3 Inputs) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / bond	Dec. 31, 2015 USD ($)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Other assets (liabilities)	$ 4,379	$ 3,463
Significant Unobservable Inputs (Level 3)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Other assets (liabilities)	(13,004)
Significant Unobservable Inputs (Level 3) | Assumed reinsurance contract | Internal Valuation Model Valuation Technique
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Liabilities, fair value	$ (574)
Significant Unobservable Inputs (Level 3) | Assumed reinsurance contract | Internal Valuation Model Valuation Technique | Low
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Bond price | $ / bond	100.82
Significant Unobservable Inputs (Level 3) | Assumed reinsurance contract | Internal Valuation Model Valuation Technique | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Bond price | $ / bond	103.58
Significant Unobservable Inputs (Level 3) | Assumed reinsurance contract | Internal Valuation Model Valuation Technique | Weighted average or actual
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Bond price | $ / bond	102.29
Liquidity discount	1.30%
Significant Unobservable Inputs (Level 3) | Assumed and ceded (re)insurance contracts | Internal Valuation Model Valuation Technique
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Liabilities, fair value	$ (12,430)
Significant Unobservable Inputs (Level 3) | Assumed and ceded (re)insurance contracts | Internal Valuation Model Valuation Technique | Low
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Contract period	2 years
Significant Unobservable Inputs (Level 3) | Assumed and ceded (re)insurance contracts | Internal Valuation Model Valuation Technique | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Contract period	4 years 7 months 27 days
Significant Unobservable Inputs (Level 3) | Assumed and ceded (re)insurance contracts | Internal Valuation Model Valuation Technique | Weighted average or actual
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Net undiscounted cash flows	$ (12,396)
Expected loss ratio	35.20%
Net acquisition expense ratio	(20.70%)
Contract period	4 years 6 months
Discount rate	1.90%