Basis of Presentation and Significant Accounting Policies (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018 segment	Jan. 01, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Aug. 14, 2017
Schedule of Equity Method Investments [Line Items]
Number of segments | segment	2
Residential Mortgage Holding Company
Schedule of Equity Method Investments [Line Items]
Ownership percentage	100.00%
NBG
Schedule of Equity Method Investments [Line Items]
Ownership percentage					50.10%
Accounting Standards Update 2016-01
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle				$ 0
Accounting Standards Update 2016-01 | Accumulated Other Comprehensive Loss
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle				(191)
Accounting Standards Update 2016-01 | Retained Earnings
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle				191
Accounting Standards Update 2017-08
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle				(62)
Accounting Standards Update 2017-08 | Retained Earnings
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle			$ (62)	$ (62)
Scenario, Forecast | Minimum | Accounting Standards Update 2016-02
Schedule of Equity Method Investments [Line Items]
Right-of-use asset		$ 15,000
Lease liabilities		15,000
Scenario, Forecast | Maximum | Accounting Standards Update 2016-02
Schedule of Equity Method Investments [Line Items]
Right-of-use asset		25,000
Lease liabilities		$ 25,000