Equity - Additional Information (Detail) - shares shares in Millions	Sep. 30, 2017	Jan. 30, 2015
Equity [Abstract]
Total shares authorized for repurchase		400
Remaining shares authorized for repurchase	192

The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

No definition available.

Name:	us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant