Fair Value of Financial Instruments (Other Investments - Pacer) (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Other investment, proceeds related to ongoing liquidation	$ 5,415	$ 13,416
Other investment, net carrying value	47,299		$ 35,763
Pacer [Member] \| Investment [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Other investment, changes in expected recovery estimates, expense	900	5,800
Other investment, proceeds related to ongoing liquidation	5,400	$ 12,100
Other investment, net carrying value	$ 3,000		$ 9,600

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