Long-Term Debt Long-Term Debt	6 Months Ended
Jun. 30, 2020
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term DebtIn March 2020, the Corporation issued $200.0 million and $175.0 million of subordinated notes due in 2030 and 2035, respectively. The subordinated notes maturing in 2030 were issued with a fixed-to-floating rate of 3.25% and an effective rate of 3.35%, due to issuance costs, and the subordinated notes maturing in 2035 were issued with a fixed-to-floating rate of 3.75% and an effective rate of 3.85%, due to issuance costs.

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-URI http://asc.fasb.org/topic&trid=2208564

Name:	us-gaap_DebtDisclosureTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration