Shareholders’ equity (Tables)

3 Months Ended

Mar. 31, 2014

Stockholders' Equity Note [Abstract]

Common and Preferred Stock Activity

See Common and Preferred Stock Activity table below for additional information about preferred stock conversions during the period.

Common and Preferred Stock Activity:	Preferred stock		Common stock
(in shares)	Series A convertible		Treasury	Outstanding
Beginning balance as of December 31, 2013	79,620		4,786,521	88,710,277
Conversion of convertible preferred stock	(255	)	—	25,542
Issuance for share-based compensation plans	—		—	35,624
Ending balance as of March 31, 2014	79,365		4,786,521	88,771,443
Beginning balance as of December 31, 2012	80,283		4,786,521	88,548,637
Conversion of convertible preferred stock	(199	)	—	19,864
Issuance for share-based compensation plans	—		—	27,708
Ending balance as of March 31, 2013	80,084		4,786,521	88,596,209