Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Goodwill	$ 2,176,291	$ 1,720,479	$ 208,743
Goodwill, Impairment Loss			(6,645)
Goodwill	2,173,949	2,176,291	1,720,479
CapitalSource Inc. [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period			$ 1,518,381
Goodwill, Subsequent Recognition of Deferred Tax Asset		7,901
Square 1 Financial, Inc. [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		$ 447,911
Goodwill Subsequent Recognition Of Tax Asset	1,842
Pacific Western Equipment Finance [Member]
Goodwill [Roll Forward]
Goodwill, Subsequent Recognition of Deferred Tax Asset	$ 500