Summary of Significant Accounting Policies Reconciliation of cash and cash equivalents (ASU 2016-18) (Tables)

12 Months Ended

Dec. 31, 2017

Reconciliation of cash and cash equivalents (ASU 2016-18) [Abstract]

Reconciliation of cash and cash equivalents (2016-18) [Table Text Block]

The following table provides a reconciliation of cash and cash equivalents, program and restricted cash reported within the Consolidated Balance Sheets to the amounts shown in the Consolidated Statements of Cash Flows:

	As of December 31,
	2017		2016
Cash and cash equivalents	$	611	$	490
Program cash	283		225
Restricted cash (a)	7		5
Total cash and cash equivalents, program and restricted cash	$	901	$	720

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^(a)  Included within other current assets.