Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2016 USD ($) branch	Dec. 31, 2019 USD ($)	Jan. 01, 2019 USD ($)		Jan. 01, 2018 USD ($)	[2]
Leases [Abstract]
Operating lease, weighted average remaining lease term			11 years 2 months 8 days
Operating lease, weighted average discount rate (as a percent)			3.19%
Right-of-use asset			$ 141,000	$ 143,600
Lessee, Lease, Description [Line Items]
Sale and leaseback transaction, number of branches sold | branch		55
Sale and leaseback transaction, pre-tax gain	$ 65,500	$ 88,000
Sale and leaseback transaction, transaction related expenses		$ 5,500
Adjustments to apply recent accounting pronouncements				47,257	[1]	$ 0
Retained Earnings
Lessee, Lease, Description [Line Items]
Adjustments to apply recent accounting pronouncements				$ 47,257	[1]	$ 6,689

[1] As a result of accounting guidance adopted in 2019, the remaining deferred gain on a sale-leaseback transaction was recognized as a cumulative-effect adjustment to retained earnings as of January 1, 2019. For further discussion of this guidance, see Note 2, "Recent Accounting Pronouncements."

[2] As a result of accounting guidance adopted in 2018, certain reclassifications were made from accumulated other comprehensive loss to retained earnings as of January 1, 2018. For further discussion of this guidance, see Note 2. "Recent Accounting Pronouncements." ⁽²⁾As a result of accounting guidance adopted in 2019, the remaining deferred gain on a sale-leaseback transaction was recognized as a cumulative-effect adjustment to retained earnings as of January 1, 2019. For further discussion of this guidance, see Note 2, "Recent Accounting Pronouncements."