Mergers and Acquisitions - Summary of Purchase Price Allocation (Details) - USD ($) $ in Thousands	Jan. 31, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Jan. 01, 2022	Dec. 31, 2021
Liabilities:
Goodwill		$ 2,631,465	$ 2,514,104	$ 2,514,104		$ 538,373
Sterling
Business Acquisition [Line Items]
Total consideration	$ 5,180,300
Assets:
Cash and due from banks	510,929
Interest-bearing deposits	3,207
Investment securities available-for-sale	4,429,948
Federal Home Loan Bank and Federal Reserve Bank Stock	150,502
Loans held for sale	23,517
Unpaid principal balance, total loans and leases		20,816,348
Total loans and leases	20,498,706
Deferred tax assets, net	(59,716)
Premises and equipment	264,421
Other intangible assets	210,100
Bank-owned life insurance policies	645,510
Accrued interest receivable and other assets	986,729
Total assets acquired	27,663,853
Liabilities:
Non-interest-bearing deposits	6,620,248
Interest-bearing deposits	16,643,755
Securities sold under agreements to repurchase and other borrowings	27,184
Long-term debt	516,881
Accrued expenses and other liabilities	589,689
Total liabilities assumed	24,397,757
Net assets acquired	3,266,096
Goodwill	1,914,204				$ 1,900,000
Sterling | Commercial non-mortgage
Assets:
Unpaid principal balance, total loans and leases		5,570,782
Total loans and leases	5,527,657
Sterling | Asset-based
Assets:
Unpaid principal balance, total loans and leases		694,137
Total loans and leases	683,958
Sterling | Commercial real estate
Assets:
Unpaid principal balance, total loans and leases		6,790,600
Total loans and leases	6,656,405
Sterling | Multi-family
Assets:
Unpaid principal balance, total loans and leases		4,303,381
Total loans and leases	4,255,906
Sterling | Equipment financing
Assets:
Unpaid principal balance, total loans and leases		1,350,579
Total loans and leases	1,314,311
Sterling | Warehouse lending
Assets:
Unpaid principal balance, total loans and leases		647,767
Total loans and leases	643,754
Sterling | Residential
Assets:
Unpaid principal balance, total loans and leases		1,313,785
Total loans and leases	1,281,637
Sterling | Home equity
Assets:
Unpaid principal balance, total loans and leases		132,758
Total loans and leases	122,553
Sterling | Other consumer
Assets:
Unpaid principal balance, total loans and leases		$ 12,559
Total loans and leases	$ 12,525