Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details) - Recurring $ in Millions	Sep. 30, 2016 USD ($)
Deferred Compensation Plan Corporate-owned Life Insurance
Assets
Corporate-owned life insurance	$ 17
Deferred Compensation Plan Corporate-owned Life Insurance | Level 1
Assets
Corporate-owned life insurance	0
Deferred Compensation Plan Corporate-owned Life Insurance | Level 2
Assets
Corporate-owned life insurance	17
Deferred Compensation Plan Corporate-owned Life Insurance | Level 3
Assets
Corporate-owned life insurance	0
Deferred Compensation Plan Stock Fund
Assets
Stuck fund and equity security	52
Deferred Compensation Plan Stock Fund | Level 1
Assets
Stuck fund and equity security	52
Deferred Compensation Plan Stock Fund | Level 2
Assets
Stuck fund and equity security	0
Deferred Compensation Plan Stock Fund | Level 3
Assets
Stuck fund and equity security	0
Equity Securities
Assets
Stuck fund and equity security	42
Equity Securities | Level 1
Assets
Stuck fund and equity security	42
Equity Securities | Level 2
Assets
Stuck fund and equity security	0
Equity Securities | Level 3
Assets
Stuck fund and equity security	0
Deferred Compensation Plan
Liabilities
Deferred compensation plans	127
Deferred Compensation Plan | Level 1
Liabilities
Deferred compensation plans	50
Deferred Compensation Plan | Level 2
Liabilities
Deferred compensation plans	77
Deferred Compensation Plan | Level 3
Liabilities
Deferred compensation plans	$ 0