Acquisitions - First Community Financial Partners, Inc. (Details) $ / shares in Units, $ in Thousands, shares in Millions			12 Months Ended
	Jul. 02, 2017 USD ($) $ / shares	Jun. 30, 2017 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Business Acquisition
Per share cash consideration entitled (in dollars per share) | $ / shares	$ 1.35
Consideration paid:
Goodwill			$ 311,536	$ 267,685
Portfolio Loans, allowance for loan losses (in dollars)			53,748	50,648	$ 53,582	$ 47,795
First Community
Business Acquisition
Share consideration conversion ratio	0.396
Number of common shares issued for acquisition | shares		7.2
Market value of common stock issued		$ 211,100
Share price | $ / shares		$ 29.32
Options to purchase common stock, conversion ratio	0.44
Assets acquired:
Cash and cash equivalents	$ 60,686
Securities	165,843
Loans held for sale	905
Portfolio loans	1,096,583
Premises and equipment	18,094
OREO	722
Other intangible assets	13,979
Other assets	41,755
Total assets acquired	1,398,567
Liabilities assumed:
Deposits	1,134,355
Other borrowings	125,751
Other liabilities	11,862
Total liabilities assumed	1,271,968
Net assets acquired	126,599
Consideration paid:
Cash	24,557
Cash payout of options and restricted stock units	6,182
Common stock	211,120
Fair value of stock options assumed	722
Total consideration paid	242,581
Goodwill	115,982
Fair value of performing loans, including loans held for sale	1,100,000
Amount expected to be accreted, gross	14,400
Contractual amount of PCI loans	17,900
Fair value of credit-impaired loans	$ 12,500
PCI loan outstanding amount			1,700
Total revenues (net interest income plus non-interest income)				316,417
Net income				$ 67,413
Diluted earnings per common share (in dollars per share) | $ / shares				$ 1.47
First Community | Non-interest expense
Business Acquisition
Business acquisition expenses			$ 100		4,500
Acquisition expenses related to professional and legal fees					$ 1,600