Shareholders' equity (Tables)

12 Months Ended

Dec. 31, 2017

Stockholders' Equity Note [Abstract]

Dividends Declared [Table Text Block]

The following table presents dividend distributions per Common Share in Swiss francs (CHF) and U.S. dollars (USD):

	Year Ended December 31
		2017			2016			2015
	CHF	USD		CHF	USD		CHF	USD
Dividends - par value reduction	—	$	—	—	$	—	0.62	$	0.65
Dividends - distributed from capital contribution reserves	2.76	2.82		2.70	2.74		1.94	2.01
Total dividend distributions per common share	2.76	$	2.82	2.70	$	2.74	2.56	$	2.66

Schedule of changes in Common Shares issued and outstanding

	Year Ended December 31
	2017		2016		2015
Shares issued, beginning of year	479,783,864		342,832,412		342,832,412
Shares issued for Chubb Corp acquisition	—		136,951,452		—
Shares issued, end of year	479,783,864		479,783,864		342,832,412
Common Shares in treasury, end of year (at cost)	(15,950,685	)	(13,815,148	)	(18,268,971	)
Shares issued and outstanding, end of year	463,833,179		465,968,716		324,563,441

Share Repurchase Program [Table Text Block]

The following table presents repurchases of Chubb's Common Shares conducted in a series of open market transactions under the Board authorizations:

	Year Ended December 31
(in millions of U.S. dollars, except share data)	2017		2016		2015
Number of shares repurchased	5,866,612		—		6,677,663
Cost of shares repurchased	$	830	$	—	$	734