Basis of Presentation (Effect of New Financial Accounting Standards) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of unrealized net gain on equity securities	$ 0
Accumulated Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of unrealized net gain on equity securities	280
Accumulated Other Comprehensive Income (Loss) | ASU 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of unrealized net gain on equity securities		$ (280)
Accumulated Other Comprehensive Income (Loss) | ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment	(4,500)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of unrealized net gain on equity securities	280
Retained Earnings | ASU 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of unrealized net gain on equity securities		$ 280
Retained Earnings | ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment	$ 4,500