Business Segments (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) segment	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	2
Condensed income statement:
Net interest income	$ 48,460,000	$ 45,651,000
Provision for credit losses	750,000	0
Noninterest Income	60,831,000	74,461,000
Noninterest expense	100,769,000	106,874,000
Income before income taxes	7,772,000	13,238,000
Income tax (benefit) expense	1,906,000	4,255,000
NET INCOME	5,866,000	8,983,000
Total assets	6,924,056,000	6,401,143,000	$ 6,742,041,000
Commercial and Consumer Banking [Member]
Segment Reporting Information [Line Items]
Maximum amount of commercial real estate loans the company would originate	10,000,000
Condensed income statement:
Net interest income	45,448,000	40,904,000
Provision for credit losses	750,000
Noninterest Income	7,096,000	9,425,000
Noninterest expense	38,272,000	36,470,000
Income before income taxes	13,522,000	13,859,000
Income tax (benefit) expense	3,316,000	4,567,000
NET INCOME	10,206,000	9,292,000
Total assets	6,140,812,000	5,583,171,000
Mortgage Banking [Member]
Condensed income statement:
Net interest income	3,012,000	4,747,000
Provision for credit losses	0
Noninterest Income	53,735,000	65,036,000
Noninterest expense	62,497,000	70,404,000
Income before income taxes	(5,750,000)	(621,000)
Income tax (benefit) expense	(1,410,000)	(312,000)
NET INCOME	(4,340,000)	(309,000)
Total assets	$ 783,244,000	$ 817,972,000