XML 48 R33.htm IDEA: XBRL DOCUMENT v3.20.4
Fair Value Measurements (Tables)
 12 Months Ended
Dec. 31, 2020
Fair Value Disclosures [Abstract]  
Fair Value, Measurement Inputs, Disclosure [Table Text Block]
Assets and liabilities measured at fair value on a recurring basis as of December 31, 2020, and 2019, are summarized in the following tables. 
December 31,
2020		Quoted Prices in
Active Markets
for Identical
Assets
(Level 1)		Significant
Other Observable
Inputs
(Level 2)		Significant
Unobservable
Inputs
(Level 3)
Available-for-sale securities$— $— $— $— 
Trading securities5 5 — — 
December 31,
2019		Quoted Prices in
Active Markets
for Identical
Assets
(Level 1)		Significant
Other Observable
Inputs
(Level 2)		Significant
Unobservable
Inputs
(Level 3)
Available-for-sale securities$5 $— $— $5 
Trading securities4 4 — — 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]
The following table summarizes changes in assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) during the twelve months ended December 31, 2020, and 2019. 
Available-for-
sale securities
Balance at December 31, 2018$6 
Return of principal on ARS(1)
Total realized/unrealized gains— 
Balance at December 31, 20195 
Return of principal on ARS(3)
Total realized/unrealized gains
Included in investment income3 
Included in other comprehensive income(4)
Balance at December 31, 2020$—