Fair Value Measurement (Quantitative Information Regarding Level 3 Valuations) (Details) - Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Corporate debt with limited observable inputs [Member]
Assets:
Fair Value at	$ 18,914	$ 14,810
Corporate debt with limited observable inputs [Member] | Market comparable securities valuation technique [Member] | Minimum [Member]
Assets:
Comparability Adjustment	0.00%
Corporate debt with limited observable inputs [Member] | Market comparable securities valuation technique [Member] | Maximum [Member]
Assets:
Comparability Adjustment	5.00%
Corporate debt with limited observable inputs [Member] | Market comparable securities valuation technique [Member] | Weighted Average [Member]
Assets:
Comparability Adjustment	2.50%
Corporate debt with limited observable inputs [Member] | Discount cash flows valuation technique [Member] | Minimum [Member]
Assets:
Comparability Adjustment	0.00%
Corporate debt with limited observable inputs [Member] | Discount cash flows valuation technique [Member] | Maximum [Member]
Assets:
Comparability Adjustment	5.00%
Corporate debt with limited observable inputs [Member] | Discount cash flows valuation technique [Member] | Weighted Average [Member]
Assets:
Comparability Adjustment	2.50%
Other asset-backed securities [Member]
Assets:
Fair Value at	$ 3,002	3,007
Other asset-backed securities [Member] | Market comparable securities valuation technique [Member] | Minimum [Member]
Assets:
Comparability Adjustment	0.00%
Other asset-backed securities [Member] | Market comparable securities valuation technique [Member] | Maximum [Member]
Assets:
Comparability Adjustment	5.00%
Other asset-backed securities [Member] | Market comparable securities valuation technique [Member] | Weighted Average [Member]
Assets:
Comparability Adjustment	2.50%
Other asset-backed securities [Member] | Discount cash flows valuation technique [Member] | Minimum [Member]
Assets:
Comparability Adjustment	0.00%
Other asset-backed securities [Member] | Discount cash flows valuation technique [Member] | Maximum [Member]
Assets:
Comparability Adjustment	5.00%
Other asset-backed securities [Member] | Discount cash flows valuation technique [Member] | Weighted Average [Member]
Assets:
Comparability Adjustment	2.50%
Other investments [Member]
Assets:
Fair Value at	$ 903	$ 3
Other investments [Member] | Discount cash flows valuation technique [Member] | Minimum [Member]
Assets:
Comparability Adjustment	0.00%
Other investments [Member] | Discount cash flows valuation technique [Member] | Maximum [Member]
Assets:
Comparability Adjustment	10.00%
Other investments [Member] | Discount cash flows valuation technique [Member] | Weighted Average [Member]
Assets:
Comparability Adjustment	5.00%