Summary of Significant Accounting Policies (New Accounting Standards) (Impact of Adoption of 2018-02) (Details) $ in Thousands	12 Months Ended
Dec. 31, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle
Reclassification of certain tax effects	$ 0
Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle
Reclassification of certain tax effects	$ 108,300

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