SUBSEQUENT EVENTS (Details) (USD $) In Thousands, except Share data, unless otherwise specified						0 Months Ended			0 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Jul. 22, 2013 Capital Source	Apr. 07, 2014 Subsequent event item	Mar. 31, 2014 Subsequent event Capital Source	Apr. 07, 2014 Subsequent event Capital Source	Apr. 07, 2014 Subsequent event Capital Source Maximum	Apr. 11, 2014 Subsequent event Capital Source Pacific Western Bank item	Apr. 07, 2014 Subsequent event Capital Source CSB item
Subsequent events
Number of operating branches							81					21
Assets	$ 6,517,853	$ 6,533,363		$ 5,299,905				$ 9,100,000
Cash receivable by stockholders of acquiree for each share of acquiree						$ 2.47
Number of shares of entity receivable by stockholders of acquiree for each share of acquiree						0.2837
Issuance of common stock (in shares)									56,700,000
Closing price of common stock (in dollars per share)									$ 45.83
Aggregate consideration paid									3,077,188
Ownership percentage by shareholders after merger							45.00%		55.00%
Number of operating branches closed as part of the integration and consolidation plan											12
Number of operating branches which overlapped with existing branches											1
Period for adjustment of fair values preliminary estimates										1 year
Goodwill	$ 208,743	$ 208,743	$ 215,862	$ 79,673	$ 79,866				$ 1,600,000