Derivatives and Hedging Activities Fair Value of Derivative Instruments With or Without Legal Rights of Offset (Details) - USD ($) $ in Thousands		Dec. 31, 2019		Dec. 31, 2018
Derivative [Line Items]
Derivative Assets, Netting Adjustments and Cash Collateral	[1],[2]	$ 144,402		$ 8,571
Derivative liability, Netting Adjustments and Cash Collateral	[1],[2]	33,534		53,752
Derivative assets		159,731		22,403
Derivative liabilities		(10,271)		(255,800)
Derivative Asset, Fair value, amount offset against collateral		158,736		22,007
Derivative Liability, Fair value, amount offset against collateral		(856)		(12,642)
Derivative Liabilities, additional net exposure, collateral pledged to counterparties in excess of net liabilities		300		639
Uncleared derivatives [Member]
Derivative [Line Items]
Derivative Asset, total gross recognized amount		4,950		12,862
Derivative Liability, total gross recognized amount		(42,199)		(306,848)
Derivative Assets, Netting Adjustments and Cash Collateral		(3,519)	[3]	(11,886)	[4]
Derivative liability, Netting Adjustments and Cash Collateral		31,928	[3]	51,048	[4]
Derivative assets		1,658		1,315
Derivative liabilities		(10,271)		(255,800)
Derivative Assets, fair value of securities pledged as collateral than can be sold or repledged		(995)	[5]	(396)	[6]
Derivative Liabilities, fair value of securities pledged as collateral that can be sold or repledged		82	[5]	6,104	[6]
Derivative Assets, fair value of securities pledged as collateral that cannot be sold or repledged		0	[5]	0	[6]
Derivative Liabilities, fair value of securities pledged as collateral that cannot be sold or repledged		9,333	[5]	237,054	[6]
Derivative Asset, Fair value, amount offset against collateral		663		919
Derivative Liability, Fair value, amount offset against collateral		(856)		(12,642)
Cleared derivatives [Member]
Derivative [Line Items]
Derivative Asset, total gross recognized amount		10,152		631
Derivative Liability, total gross recognized amount		(1,606)		(2,704)
Derivative Assets, Netting Adjustments and Cash Collateral		147,921	[3]	20,457	[4]
Derivative liability, Netting Adjustments and Cash Collateral		1,606	[3]	2,704	[4]
Derivative assets		158,073		21,088
Derivative liabilities		0		0
Derivative Assets, fair value of securities pledged as collateral than can be sold or repledged		0	[5]	0	[6]
Derivative Liabilities, fair value of securities pledged as collateral that can be sold or repledged		0	[5]	0	[6]
Derivative Assets, fair value of securities pledged as collateral that cannot be sold or repledged		0	[5]	0	[6]
Derivative Liabilities, fair value of securities pledged as collateral that cannot be sold or repledged		0	[5]	0	[6]
Derivative Asset, Fair value, amount offset against collateral		158,073		21,088
Derivative Liability, Fair value, amount offset against collateral		0		0
Mortgage Receivable [Member] | Uncleared derivatives [Member] | Mortgage-delivery commitments [Member]
Derivative [Line Items]
Derivative Asset, Mortgage delivery commitments		227		339
Derivative Liabilities, Mortgage delivery commitments		$ 0		$ 0

[1] Amounts represent the effect of master-netting agreements intended to allow us to settle positive and negative positions with the same counterparty. Cash collateral and related accrued interest posted was $178.5 million and $62.8 million at December 31, 2019, and 2018, respectively. The change in cash collateral posted is included in the net change in interest-bearing deposits in the statement of cash flows. Cash collateral and related accrued interest received was $561 thousand and $471 thousand at December 31, 2019 and 2018.

[2] These amounts represent the effect of master-netting agreements intended to allow us to settle positive and negative positions and also cash collateral and related accrued interest held or placed with the same clearing member and/or counterparty.

[3] Includes gross amounts of netting adjustments and cash collateral.

[4] Includes gross amounts of netting adjustments and cash collateral.

[5] Includes non-cash collateral at fair value. Any overcollateralization with a counterparty is not included in the determination of the net amount. At December 31, 2019, we had additional net credit exposure of $300 thousand due to instances where our collateral pledged to a counterparty exceeded our net derivative liability position.

[6] Includes non-cash collateral at fair value. Any overcollateralization with a counterparty is not included in the determination of the net amount. At December 31, 2018, we had additional net credit exposure of $639 thousand due to instances where our collateral pledged to a counterparty exceeded our net derivative liability position.