Other Assets - Derivative Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments
Derivative assets, fair value	$ 679	$ 233
Non-cleared Interest Rate Swap \| Hedging \| Assets
Derivative Instruments
Notional amount of derivative assets	0	350,000
Derivative assets, fair value	0	233
Cleared Interest Rate Swap \| Hedging \| Assets
Derivative Instruments
Notional amount of derivative assets	750,000	0
Derivative assets, fair value	679	0
Cleared Interest Rate Swap \| Hedging \| Liabilities
Derivative Instruments
Notional amount of derivative liabilities	1,800,000	2,550,000
Derivative liabilities, at fair value	$ 0	$ (46,954)

Nominal or face amount used to calculate payments on the derivative asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Topic 815
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
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Fair value, after offset of derivative asset, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Nominal or face amount used to calculate payments on the derivative liability.

+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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