Fair Values of Financial Instruments (Reconciliation of Recurring Fair Value Measurements Recognized in Balance Sheet using Significant Unobservable (Level Three) Inputs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Values of Financial Instruments [Abstract]
Beginning balance	$ 2,534	$ 2,522	$ 3,336
Total realized and unrealized gains (losses)
Included in net income			(68)
Included in other comprehensive income (loss)	54	12	2,098
Sales			(2,826)
Settlements			(18)
Ending balance	2,588	2,534	2,522
Total gains or losses for the period included in net income attributable to the change in unrealized gains or losses related to assets still held at the reporting date	$ 0	$ 0	$ 0