Derivative Financial Instruments (Credit Related Derivative Contracts) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Index credit default swaps [Member]
Derivative [Line Items]
Notional amount	$ 1,441	$ 146
Single name credit default swaps [Member]
Derivative [Line Items]
Notional amount	331	383
Investment Grade [Member] | Index credit default swaps [Member]
Derivative [Line Items]
Notional amount	1,103	54
Investment Grade [Member] | Single name credit default swaps [Member]
Derivative [Line Items]
Notional amount	139	122
Non-investment grade [Member] | Index credit default swaps [Member]
Derivative [Line Items]
Notional amount	338	92
Non-investment grade [Member] | Single name credit default swaps [Member]
Derivative [Line Items]
Notional amount	$ 192	$ 261