Label	Element	Value
Fair Value, Recurring [Member] | Certificates of Deposit [Member]
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	$ 2,000,000
Fair Value, Recurring [Member] | Money Market Funds [Member]
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	42,000,000
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	99,000,000
Fair Value, Recurring [Member] | US Treasury Securities [Member]
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	12,000,000
Fair Value, Recurring [Member] | Commercial Paper [Member]
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	14,000,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Certificates of Deposit [Member]
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Money Market Funds [Member]
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	99,000,000
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	42,000,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US Treasury Securities [Member]
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Commercial Paper [Member]
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	14,000,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Certificates of Deposit [Member]
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	2,000,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Money Market Funds [Member]
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	0
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US Treasury Securities [Member]
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	12,000,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Commercial Paper [Member]
Restricted Cash Equivalents	us-gaap_RestrictedCashEquivalents	$ 0