Label	Element	Value
Private Capital [Member]
Proceeds from Issuance of Private Placement	us-gaap_ProceedsFromIssuanceOfPrivatePlacement	$ 382,900,000
Preferred Stock [Member]
Proceeds from Issuance Initial Public Offering	us-gaap_ProceedsFromIssuanceInitialPublicOffering	498,516,000
Additional Paid-in Capital [Member] | Private Capital [Member]
Proceeds from Issuance of Private Placement	us-gaap_ProceedsFromIssuanceOfPrivatePlacement	$ 382,575,000
Voting Common Stock [Member]
Common Stock, Shares, Outstanding	us-gaap_CommonStockSharesOutstanding	78,555,290
Voting Common Stock [Member] | Common Stock [Member] | Private Capital [Member]
Proceeds from Issuance of Private Placement	us-gaap_ProceedsFromIssuanceOfPrivatePlacement	$ 217,000
Common Stock, Shares, Issued	us-gaap_CommonStockSharesIssued	21,690,334
Nonvoting Common Stock Equivalents [Member] | Common Stock [Member] | Private Capital [Member]
Proceeds from Issuance of Private Placement	us-gaap_ProceedsFromIssuanceOfPrivatePlacement	$ 108,000
Common Stock, Shares, Issued	us-gaap_CommonStockSharesIssued	10,829,990
Pacific Western Bank [Member]
Proceeds from Issuance of Common Stock	us-gaap_ProceedsFromIssuanceOfCommonStock	$ 663,004,000
Pacific Western Bank [Member] | Additional Paid-in Capital [Member]
Proceeds from Issuance of Common Stock	us-gaap_ProceedsFromIssuanceOfCommonStock	662,869,000
Pacific Western Bank [Member] | Voting Common Stock [Member] | Common Stock [Member]
Proceeds from Issuance of Common Stock	us-gaap_ProceedsFromIssuanceOfCommonStock	$ 130,000
Common Stock, Shares, Issued	us-gaap_CommonStockSharesIssued	57,157,632
Pacific Western Bank [Member] | Class B Nonvoting [Member] | Common Stock [Member]
Proceeds from Issuance of Common Stock	us-gaap_ProceedsFromIssuanceOfCommonStock	$ 5,000
Common Stock, Shares, Issued	us-gaap_CommonStockSharesIssued	477,321