Summary of Significant Accounting Policies (Adopted Accounting Pronouncements) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)	[1]
New Accounting Pronouncement, Early Adoption [Line Items]
Reclassification of certain income tax effects	$ 0
Retained Earnings
New Accounting Pronouncement, Early Adoption [Line Items]
Reclassification of certain income tax effects	$ 4,518

[1] The reclassification from accumulated other comprehensive income (loss) to retained earnings was due to the early adoption of ASU 2018-02, refer to Note 1 for further details on the adoption.