Available for Sale Securities and Other Investments (Amortized Cost, Gross Unrealized Gains and Losses and Estimated Fair Value of Available for Sale Investments) (Details) - USD ($) $ in Thousands	May 31, 2019	Nov. 30, 2018
Schedule of Investments [Line Items]
Amortized Cost		$ 1,411,762
Gross Unrealized Gains		378
Gross Unrealized Losses		2,254
Estimated Fair Value	$ 0	1,409,886
U.S. government securities
Schedule of Investments [Line Items]
Amortized Cost		1,073,038
Gross Unrealized Gains		1
Gross Unrealized Losses		183
Estimated Fair Value		1,072,856
Residential mortgage-backed securities
Schedule of Investments [Line Items]
Amortized Cost		211,209
Gross Unrealized Gains		376
Gross Unrealized Losses		1,067
Estimated Fair Value		210,518
Commercial mortgage-backed securities
Schedule of Investments [Line Items]
Amortized Cost		16,068
Gross Unrealized Gains		0
Gross Unrealized Losses		426
Estimated Fair Value		15,642
Other asset-backed securities
Schedule of Investments [Line Items]
Amortized Cost		111,447
Gross Unrealized Gains		1
Gross Unrealized Losses		578
Estimated Fair Value		$ 110,870

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
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