REPURCHASE AGREEMENTS AND OTHER BORROWINGS (Narrative) (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Assets Sold under Agreements to Repurchase [Line Items]
Outstanding repurchase obligations	$ 3,025,052,000	$ 3,533,786,000
Fair Value of securities pledged, including accrued interest receivable	3,214,369,000	3,726,523,000
Restricted cash	$ 17,981,000	$ 32,349,000
Net weighted average borrowing rate	2.65%	1.54%
Repurchase Agreement [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Outstanding repurchase obligations	$ 3,025,052,000	$ 3,533,786,000
Fair Value of securities pledged, including accrued interest receivable	3,214,369,000	3,726,523,000
Restricted cash	$ 7,034,000	$ 25,296,000
Net weighted average borrowing rate	2.65%	1.54%
Aggregate amount at risk will all counterparties	$ 189,900,000