Marketable securities (Tables)

3 Months Ended

Mar. 31, 2013

Investments Debt And Equity Securities [Abstract]

Schedule of Marketable Securities

	Market value		Cost basis		Unrealized gains, net
	(In millions)
December 31, 2012:
Current assets:	$	.9	$	.9	$	—
Noncurrent assets:
The Amalgamated Sugar Company LLC	$	250.0	$	250.0	$	—
Other		6.8		6.7		.1
Total	$	256.8	$	256.7	$	.1
March 31, 2013:
Current assets	$	.9	$	.9	$	—
Noncurrent assets:
The Amalgamated Sugar Company LLC	$	250.0	$	250.0	$	—
Other		6.7		6.6		.1
Total	$	256.7	$	256.6	$	.1