Accounting Policies - Summary of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash accounts, Amount	$ 571,587	$ 549,639
Money market funds, Amount	341,085	322,455
Total	$ 912,672	$ 872,094
Cash
Percent Of Cash And Cash Equivalents	62.60%	63.00%
Money Market Funds
Percent Of Cash And Cash Equivalents	37.40%	37.00%

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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