Operating Lease Right-of-Use Assets and Liabilities - Narrative (Details) - USD ($) $ in Thousands	May 31, 2019	Dec. 31, 2019	Aug. 01, 2019
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets		$ 118,700
Lease liabilities		138,393
Leases not yet commenced, amount		233,600
Ownership percentage	50.00%
Chemical Financial Corporation
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets			$ 39,800
Lease liabilities			$ 41,600
Corporate Headquarters
Lessee, Lease, Description [Line Items]
Leases not yet commenced, amount		$ 231,600
Leases not yet commenced, term		22 years 6 months