Dividend Availability and Regulatory Matters Dividend Availability and Regulatory Matters (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Compliance with Regulatory Capital Requirements for Mortgage Companies [Line Items]
Proceeds from Dividends Received	$ 259,000,000
Retained earnings	$ 366,073,000	$ 13,907,000
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%
Tier One Risk Based Common Equity Required to be Adequately Capitalized to Risk Weighted Assets	4.50%
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Tier One Risk Based Capital Required to be Well Capitalized	6.50%	6.50%
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Deferred Tax Assets, Regulatory Assets and Liabilities	$ 2,100,000
Subordinated debentures	440,744,000	$ 436,000,000
Tier One Capital, Trust Preferred Securities Capital Portion	0
Tier Two Capital, Trust Preferred Securities Capital Portion	428,200,000
Pacific Western Bank [Member]
Compliance with Regulatory Capital Requirements for Mortgage Companies [Line Items]
Retained earnings	520,000,000
Deferred Tax Assets, Regulatory Assets and Liabilities	$ 200,000.0