Credit Risk and Interest Rate Risk (Tables)

12 Months Ended

Dec. 31, 2017

Offsetting [Abstract]

Schedule of Assets and Liabilities Subject to Netting Arrangements

The following table presents information about our liabilities that are subject to such arrangements and can potentially be offset on our consolidated statements of financial condition as of December 31, 2017 and December 31, 2016.

	December 31, 2017
	(dollars in thousands)
	Gross Amounts of Recognized  Assets (Liabilities)			Gross Amounts Offset in the Consolidated Statements of Financial Position			Net Amounts Offset in the Consolidated Statements of Financial Position			Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position
										Financial Instruments		Cash Collateral (Received) Pledged (1)		Net Amount
Repurchase Agreements	$	(7,250,452	)	$	—		$	(7,250,452	)	$	8,788,680	$	1,156	$	1,539,384
Interest Rate Swaps - Gross Assets	44,874			(1,617		)	43,257			—		11,570		54,827
Interest Rate Swaps - Gross Liabilities	(1,617		)	1,617			—			—		—		—
Treasury Futures - Gross Assets	3,552			—			3,552			—		376		3,928
Treasury Futures - Gross Liabilities	—			—			—			—		—		—
Swaptions - Gross Assets	2,105			—			2,105			—		—		2,105
Swaptions - Gross Liabilities	(320		)	—			(320		)	—		—		(320		)
Total Liabilities	$	(7,201,858	)	$	—		$	(7,201,858	)	$	8,788,680	$	13,102	$	1,599,924

(1) Included in other assets

	December 31, 2016
	(dollars in thousands)
	Gross Amounts of Recognized  Assets (Liabilities)			Gross Amounts Offset in the Consolidated Statements of Financial Position			Net Amounts Offset in the Consolidated Statements of Financial Position			Gross Amounts Not Offset with Financial Assets (Liabilities) in the Consolidated Statements of Financial Position
										Financial Instruments		Cash Collateral (Received) Pledged (1)		Net Amount
Repurchase Agreements	$	(5,600,903	)	$	—		$	(5,600,903	)	$	7,033,866	$	2,545	$	1,435,508
Interest Rate Swaps - Gross Assets	14,435			(14,435		)	—			—		—		—
Interest Rate Swaps - Gross Liabilities	(14,875		)	14,875			—			—		39,627		39,627
Treasury Futures - Gross Assets	1,785			—			1,785			—		3,320		5,105
Treasury Futures - Gross Liabilities	—			—			—			—		—		—
Swaptions - Gross Assets	7,892			—			7,892			—		—		7,892
Swaptions - Gross Liabilities	(2,350		)	—			(2,350		)	10,341		—		7,991
Total Liabilities	$	(5,594,016	)	$	440		$	(5,593,576	)	$	7,044,207	$	45,492	$	1,496,123

(1) Included in other assets