Summary of Significant Accounting Policies, Accounting Changes (Details) - Accounting Standards Update 2018-12 $ in Billions	Jan. 01, 2021 USD ($)
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in AOCI	$ 2.0
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in AOCI	$ 2.3

Amount of increase (decrease) in accumulated other comprehensive income.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=124509347&loc=SL7669686-108580

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=124431353&loc=SL124442411-227067

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Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration