XML 96 R81.htm IDEA: XBRL DOCUMENT v3.8.0.1

Derivative Instruments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017
Commodity Futures Contracts
Trading Activity, Gains and Losses, Net [Line Items]
Reclassification period for effective portion of contract, in years	1 year

X

- Definition

Reclassification period for effective portion of contract.

+ References

No definition available.

+ Details

Name:	aos_ReclassificationPeriodForEffectivePortionOfContract
Namespace Prefix:	aos_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_TradingActivityGainsAndLossesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_TradingActivityByTypeAxis=aos_CommodityFuturesContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: