Dividend Availability and Regulatory Matters Textuals (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Compliance with Regulatory Capital Requirements for Mortgage Companies [Line Items]
Proceeds from Dividends Received	$ 137,000,000us-gaap_ProceedsFromDividendsReceived
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.00%
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.00%	6.00%
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Deferred Tax Assets, Regulatory Assets and Liabilities	156,700,000
Subordinated debentures	433,583,000us-gaap_SubordinatedDebt	132,645,000us-gaap_SubordinatedDebt
Proceeds from Issuance of Trust Preferred Securities	131,000,000
Pacific Western Bank [Member]
Compliance with Regulatory Capital Requirements for Mortgage Companies [Line Items]
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Deferred Tax Assets, Regulatory Assets and Liabilities	0
Subordinated Debt [Member]
Compliance with Regulatory Capital Requirements for Mortgage Companies [Line Items]
Subordinated debentures	433,583,000	132,645,000
CapitalSource Inc. [Member] \| Subordinated Debt [Member]
Compliance with Regulatory Capital Requirements for Mortgage Companies [Line Items]
Subordinated debentures	$ 300,400,000

The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 505

-Section 50

-Paragraph 1H

-Subparagraph (c)(2)

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences derived regulatory assets and liabilities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

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- Definition

Dividends received on equity and other investments during the current period.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (b)

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The cash inflow from issuance of preferred stocks by a business trust or other special purpose entity, mainly established by a bank holding entity, to third party investors. The trust's assets are deeply subordinated debentures of the bank holding entity. Most trust preferred securities are subject to a mandatory redemption upon the repayment of the debentures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 10

-Section F

Reference 5: http://www.xbrl.org/2003/role/presentationRef

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-Name Regulation S-X (SX)

-Number 210

-Section 02

-Article 5

-Subsection 19, 20, 22

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- Definition

The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

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The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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