Borrowings (Repurchase Agreements) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Borrowing Balance	$ 672,395	$ 795,354
Securities Sold under Agreements to Repurchase [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 530,440	$ 652,229
Weighted Average Coupon	1.44%
Securities Sold under Agreements to Repurchase [Member] \| Due date: 4/4/2017 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 33,460
Weighted Average Coupon	1.20%
Settlement Date	Mar. 21, 2017
Investment Repurchase Agreement, Repurchase Date	Apr. 04, 2017
Securities Sold under Agreements to Repurchase [Member] \| Due Date: 4/3/2017 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 62,480
Weighted Average Coupon	1.21%
Settlement Date	Mar. 30, 2017
Investment Repurchase Agreement, Repurchase Date	Apr. 03, 2017
Securities Sold under Agreements to Repurchase [Member] \| Due Date: 4/7/2017 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 32,000
Weighted Average Coupon	0.99%
Settlement Date	Mar. 31, 2017
Investment Repurchase Agreement, Repurchase Date	Apr. 07, 2017
Securities Sold under Agreements to Repurchase [Member] \| Due Date: 04 29 2018 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 192,500
Weighted Average Coupon	1.42%
Settlement Date	Dec. 10, 2012
Investment Repurchase Agreement, Repurchase Date	Apr. 29, 2018
Securities Sold under Agreements to Repurchase [Member] \| Due date: 06 09 2019 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 25,000
Weighted Average Coupon	1.52%
Settlement Date	Dec. 09, 2016
Investment Repurchase Agreement, Repurchase Date	Jun. 09, 2019
Securities Sold under Agreements to Repurchase [Member] \| Due date; 12/09/2019 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 75,000
Weighted Average Coupon	1.462%
Settlement Date	Dec. 09, 2016
Investment Repurchase Agreement, Repurchase Date	Dec. 09, 2019
Securities Sold under Agreements to Repurchase [Member] \| Due Date: 9/3/2019 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 50,000
Weighted Average Coupon	1.72%
Settlement Date	Mar. 02, 2017
Investment Repurchase Agreement, Repurchase Date	Sep. 03, 2019
Securities Sold under Agreements to Repurchase [Member] \| Due Date: 3/2/2020 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 60,000
Weighted Average Coupon	1.85%
Settlement Date	Mar. 02, 2017
Investment Repurchase Agreement, Repurchase Date	Mar. 02, 2020

Date the repurchase agreement was made.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 12
-Footnote 2

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Date the repurchase will be made.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 12
-Footnote 2

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Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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