Accumulated Other Comprehensive Income (Loss) (Components of unrealized holding gains on AFS securities) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 7,567	$ (1,871)	$ 7,567	$ (1,871)	$ 5,018	$ 221	$ 2,484	$ (506)
Unrealized gains (losses) on AFS securities arising during the period	4,067	(6,520)	11,341	(2,164)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax	(245)	0	(245)	0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent	3,670	(6,520)	10,944	(2,164)
Net unrealized gains (losses)	3,670	(6,520)	10,944	(2,164)
Tax effect (1)	(1,121)	2,165	(3,598)	799
Unrealized gains (losses), net of tax	2,549	(4,355)	7,346	(1,365)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	3,915	(6,520)	11,189	(2,164)
Other Comprehensive Income (Loss), Tax	(1,121)	2,165	(3,598)	799
Unrealized Holding Gains (Losses) on AFS Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	10,982	1,937	10,982	1,937	8,333	3,536	6,292	3,302
Unrealized gains (losses) on AFS securities arising during the period	4,067	(6,520)		(2,164)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax	(245)	0		0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent	3,822	(6,520)	11,096	(2,164)
Net unrealized gains (losses)	3,822	(6,520)	11,096	(2,164)
Tax effect (1)	1,173	(2,165)	3,650
Unrealized gains (losses), net of tax	2,649	(4,355)	7,446	(1,365)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	4,067	(6,520)	11,341	(2,164)
Other Comprehensive Income (Loss), Tax	(1,173)	2,165	(3,650)	799
Unrealized Holding Gains (Losses) on AFS Securities [Member] | Auction Rate Money Market Preferred and Preferred Stocks [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized gains (losses) on AFS securities arising during the period	372	360	360	190
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax	0	0	0	0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent	372	360	360	190
Tax effect (1)	0	0	0	0
Unrealized gains (losses), net of tax	372	360	360	190
Unrealized Holding Gains (Losses) on AFS Securities [Member] | All Other AFS Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized gains (losses) on AFS securities arising during the period	3,695	(6,880)	10,981	(2,354)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax	(245)	0	(245)	0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent	3,450	(6,880)	10,736	(2,354)
Tax effect (1)	1,173	(2,165)	3,650	(799)
Unrealized gains (losses), net of tax	2,277	(4,715)	7,086	(1,555)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(3,315)	(3,808)	(3,315)	(3,808)	$ (3,315)	$ (3,315)	$ (3,808)	$ (3,808)
Net unrealized gains (losses)	0	0	0	0
Unrealized gains (losses), net of tax	0	0	0	0
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0	0	0	0
Other Comprehensive Income (Loss), Tax	$ 0	$ 0	$ 0	$ 0