Goodwill and Other Intangible Assets - Narrative (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jun. 01, 2020
Goodwill [Line Items]
Goodwill		$ 901,312,000	$ 898,569,000	$ 808,322,000
Purchase accounting adjustments		2,743,000	(2,597,000)
Impairment losses			0
Net intangible assets		69,571,000	85,507,000	83,312,000
Additions due to acquisitions		0	19,267,000	$ 0
Estimated amortization expense for 2021		14,000,000
Estimated amortization expense for 2022		12,300,000
Estimated amortization expense for 2023		11,100,000
Estimated amortization expense for 2024		10,000,000
Estimated amortization expense for 2025		8,900,000
Core Deposits
Goodwill [Line Items]
Net intangible assets		$ 66,900,000	82,500,000
Core Deposits | Minimum
Goodwill [Line Items]
Weighted average useful life (in years)		6 years
Core Deposits | Maximum
Goodwill [Line Items]
Weighted average useful life (in years)		11 years
Customer Relationships
Goodwill [Line Items]
Net intangible assets		$ 2,700,000	3,000,000
Opus
Goodwill [Line Items]
Goodwill					$ 92,990,000
Purchase accounting adjustments	$ (146,000)	2,700,000
Additions due to acquisitions		$ 0	19,300,000
Intangible assets					19,267,000
Opus | Core Deposits
Goodwill [Line Items]
Intangible assets					16,100,000
Opus | Customer Relationships
Goodwill [Line Items]
Intangible assets					$ 3,200,000
Grandpoint Capital, Inc.
Goodwill [Line Items]
Purchase accounting adjustments			$ (2,600,000)