Fair Value of Financial Instruments, Rollforward of Balance Sheet Amounts Within Level 3 Valuation Hierarchy (Details) - Recurring [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Other Liabilities [Member]
Assets measured on recurring basis, unobservable input reconciliation, calculation [Roll Forward]
Fair value, beginning of period	$ 0	$ 0
Total realized gains included in income	0	0
Change in unrealized gains/losses included in other comprehensive income for assets and liabilities still held at period end	0	0
Purchases	0	0
Issuances	0	0
Settlements	0	0
Transfers out of Level 3	0	0
Fair value, end of period	0	0
Total realized gains included in income related to financial assets and liabilities still on the consolidated balance sheet at period end	0	0
Other Assets [Member]
Assets measured on recurring basis, unobservable input reconciliation, calculation [Roll Forward]
Fair value, beginning of period	10,478	9,764
Total realized gains included in income	197	177
Change in unrealized gains/losses included in other comprehensive income for assets and liabilities still held at period end	0	0
Purchases	120	325
Issuances	0	0
Settlements	(303)	(138)
Transfers out of Level 3	0	0
Fair value, end of period	10,492	10,128
Total realized gains included in income related to financial assets and liabilities still on the consolidated balance sheet at period end	$ 197	$ 177