Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Level 3 Inputs) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of the period		$ 1,719
Total unrealized losses
Included in net investment income		(118)
Total realized gains
Included in other income		1,700
Purchases		(525)
Balance at end of the period		2,776
Net investment income
Total realized gains
Change in unrealized gains for the period included in earnings for assets held at the end of the period		(118)
Other assets and (liabilities)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of the period	$ (13,004)	(5,899)
Total unrealized losses
Included in net investment income		0
Total realized gains
Included in other income	1,071	1,700
Purchases	(202)	(525)
Balance at end of the period	$ (12,135)	(4,724)
Other assets and (liabilities) | Net investment income
Total realized gains
Change in unrealized gains for the period included in earnings for assets held at the end of the period		0
Fixed maturity investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of the period		7,618
Total unrealized losses
Included in net investment income		(118)
Total realized gains
Included in other income		0
Purchases		0
Balance at end of the period		7,500
Fixed maturity investments | Net investment income
Total realized gains
Change in unrealized gains for the period included in earnings for assets held at the end of the period		$ (118)