Goodwill and Intangible Assets Acquisitions (Details) - USD ($) shares in Millions, $ in Millions			12 Months Ended
	Oct. 01, 2018	May 01, 2018	Dec. 31, 2019
CoBiz Financial Inc. [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Oct. 01, 2018
Name of Acquired Entity			CoBiz Financial, Inc. ("CoBiz")
Consideration Transferred			$ 944.0
Cash payments to acquire businesses			$ 243.0
Stock Issued During Period, Shares, Acquisitions			7.2
Equity interests issued			$ 701.0
Goodwill Recognized, Description			synergies expected to be gained through consolidation of administrative functions resulting in cost savings.
Switchgrass Holdings LLC [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition		May 01, 2018
Name of Acquired Entity			Switchgrass Holdings, LLC
Cash payments to acquire businesses			$ 14.0
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest [Abstract]
Intangible assets			$ 6.7