SUBSEQUENT EVENTS (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	9 Months Ended
		Oct. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Jul. 31, 2019	Jun. 30, 2019	Apr. 30, 2019	Jan. 31, 2019	Dec. 31, 2018	[2]	Oct. 31, 2018	Jul. 31, 2018	Mar. 31, 2018
Subsequent Event [Line Items]
Preferred stock, redemption price (in dollars per share)			$ 25.00
Loans	[1]		$ 3,946,614						$ 4,585,975
OBX Trust | Consolidated VIEs
Subsequent Event [Line Items]
Loans					$ 463,405	$ 383,760	$ 388,156	$ 393,961			$ 384,027	$ 383,451	$ 327,162
Series C
Subsequent Event [Line Items]
Preferred stock to be redeemed (in shares)			7,000,000.0	5,000,000.0
Preferred stock, redemption price (in dollars per share)			$ 25.00
Subsequent Event
Subsequent Event [Line Items]
Stock repurchased (in shares)		7,900,000
Stock repurchased, value		$ 68,200
Subsequent Event | OBX Trust | Consolidated VIEs
Subsequent Event [Line Items]
Loans		$ 465,500

[1] ⁽⁴⁾  Includes $76.3 million and $97.5 million of residential mortgage loans held for sale and $0 and $42.2 million of commercial mortgage loans held for sale at September 30, 2019 and December 31, 2018, respectively.

[2] ⁽¹⁾  Derived from the audited consolidated financial statements at December 31, 2018.