Cash and Cash Equivalents (Narrative) (Details)	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Average annual interest rates	0.88%	2.41%

The weighted average interest rate for domestic savings deposit liabilities.

No definition available.

Name:	us-gaap_WeightedAverageRateDomesticDepositSavings
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant