Goodwill and Other Intangible Assets, Summary of Core Deposit and Other Intangibles (Details) - USD ($)	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Summary of core deposit intangibles and other intangibles
Additions during the period		$ 162,000		$ 1,000,000
Amortization of other intangible assets	$ 450,000		$ 525,000		$ 1,459,000	$ 1,568,000
Core Deposit Intangibles
Summary of core deposit intangibles and other intangibles
Gross carrying amount	4,385,000				4,385,000		$ 4,385,000
Accumulated amortization	(4,385,000)				(4,385,000)		(4,273,000)
Total Estimated Amortization Expense	0				0		112,000
Amortization of other intangible assets					112,000		281,000
Other Intangible Assets
Summary of core deposit intangibles and other intangibles
Gross carrying amount	32,572,000				32,572,000		32,410,000
Accumulated amortization	(18,492,000)				(18,492,000)		(17,145,000)
Total Estimated Amortization Expense	$ 14,080,000				14,080,000		15,265,000
Additions during the period					162,000		1,012,000
Amortization of other intangible assets					$ 1,347,000		$ 1,812,000