Dispositions and Held-for-Sale (Dispositions) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Mar. 17, 2018 banking_branch	Mar. 16, 2018 USD ($)
Disposition [Line Items]
Net gain on sale of business	$ 31,470	$ 0
Desert Community Bank
Disposition [Line Items]
Net cash payment in sale of branches	499,900
Net gain on sale of business	$ 31,500
Desert Community Bank | California
Disposition [Line Items]
Number of branches sold | banking_branch			8
Loans | Desert Community Bank
Disposition [Line Items]
Branch assets sold				$ 59,100
Cash and cash equivalents | Desert Community Bank
Disposition [Line Items]
Branch assets sold				9,000
Premises and equipment | Desert Community Bank
Disposition [Line Items]
Branch assets sold				7,900
Deposits | Desert Community Bank
Disposition [Line Items]
Branch liabilities sold				$ 613,700