Fair Value Measurements (Quantitative Information Used As Level 3 Inputs) (Details) - Internal Valuation Model Valuation Technique - Significant Unobservable Inputs (Level 3) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) $ / bond
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Other assets and (liabilities)	$ (12,135)
Assumed reinsurance contract
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Other assets and (liabilities)	$ (180)
Assumed reinsurance contract | Low
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Bond price | $ / bond	101.02
Assumed reinsurance contract | High
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Bond price | $ / bond	107.15
Assumed reinsurance contract | Weighted Average or Actual
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Bond price | $ / bond	104.41
Liquidity discount	1.30%
Assumed and ceded (re)insurance contract
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Other assets and (liabilities)	$ (11,955)
Assumed and ceded (re)insurance contract | Low
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Contract period	2 years
Assumed and ceded (re)insurance contract | High
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Contract period	4 years 7 months 27 days
Assumed and ceded (re)insurance contract | Weighted Average or Actual
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Net undiscounted cash flows	$ (12,620)
Expected loss ratio	33.10%
Net acquisition expense ratio	(20.50%)
Contract period	4 years 6 months
Discount rate	1.90%