Acquisitions (Details Textuals) (USD $)	3 Months Ended										12 Months Ended					0 Months Ended		9 Months Ended		0 Months Ended	1 Months Ended	0 Months Ended
	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012	Apr. 07, 2014 bank_branch	Apr. 07, 2014 bank_branch	Dec. 31, 2014		May 31, 2013	May 31, 2013 bank_branch	Aug. 01, 2012	Aug. 01, 2012	Apr. 03, 2012	Apr. 03, 2012	Jan. 03, 2012	Jan. 03, 2012	Dec. 31, 2011
Business Acquisition [Line Items]
Common Stock, Par or Stated Value Per Share	$ 0.01					$ 0.01					$ 0.01		$ 0.01					$ 0.01
Goodwill	$ 1,720,479,000	[1]				$ 208,743,000	[1]				$ 1,720,479,000	[1]	$ 208,743,000	[1]	$ 79,866,000			$ 1,720,479,000	[1]									$ 39,141,000
Goodwill, Impairment Loss											6,645,000
Impairment of Intangible Assets, Finite-lived											804,000		0		0
Acquisition, integration and reorganization costs	83,021,000		85,609,000	83,167,000	50,530,000	49,984,000		51,170,000	46,233,000	43,991,000	101,016,000		40,812,000		4,089,000
Capitalsource, Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition											Apr. 07, 2014						Apr. 07, 2014
Total consideration paid																3,077,188,000	3,077,188,000
Business Acquisition, Share Price																$ 2.47	$ 2.47
Business Acquisition Shares Receivable By Stockholders Of Acquiree Ratio																0.2837	0.2837
Common Stock, Par or Stated Value Per Share																$ 45.83	$ 45.83
Common Stock, Value, Outstanding																3,100,000,000	3,100,000,000
Business Integration Completion Date																April 12, 2014
Number of Branches																21	21
Number Of Operating Branches Closed As Part Of Integration And Consolidation Plan																12	12
Number Of Operating Branches Which Overlapped With Existing Branches																1	1
Goodwill																1,518,381,000	1,518,381,000
Pro forma revenues (net interest income plus noninterest income)																		400,600,000
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual																		184,600,000
First California Financial Group, Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition																				May 31, 2013
Total consideration paid																				251,568,000	251,568,000
Number of Branches																				15	15
Goodwill																				129,070,000	129,070,000
Number Of Locations Added To Branch Network As Result Of Integration And Consolidation Plan																				7	7
American Perspective Bank [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition																						Aug. 01, 2012
Total consideration paid																						58,076,000	58,076,000
Goodwill																						15,047,000	15,047,000
Celtic Capital Corporation [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition																								Apr. 03, 2012
Total consideration paid																								18,000,000	18,000,000
Goodwill																								6,645,000	6,645,000
Asset Based Lending Maximum																								5,000,000	5,000,000
Goodwill, Impairment Loss				(6,600,000)
Pacific Western Equipment Finance [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition																										Jan. 03, 2012
Total consideration paid																										35,000,000	35,000,000
Goodwill																										19,033,000	19,033,000
Shares Of Common Stock [Member] | Capitalsource, Inc. [Member]
Business Acquisition [Line Items]
Stock Issued During Period, Shares, New Issues																56,600,000
Vesting Based On Service [Member] | Restricted Stock [Member]
Business Acquisition [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost											26,100,000		12,400,000
CDI and CRI [Member]
Business Acquisition [Line Items]
Impairment of Intangible Assets, Finite-lived											1,300,000		0		0
CDI and CRI [Member] | Celtic Capital Corporation [Member]
Business Acquisition [Line Items]
Impairment of Intangible Assets, Finite-lived				$ 500,000

[1] (1)The increase in the goodwill for the Community Banking segment and National Lending segment during 2014 was due primarily to $1.5 billion from the CapitalSource merger.