Supplemental balance sheet and cash flow information (other) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Other non-current assets [Abstract]
Contract acquisition costs	$ 55,076		$ 57,476		$ 45,701
Deferred advertising costs	15,599		15,832
Other	29,923		20,939
Other non-current assets	100,598		94,247
Contract acquisition costs [Roll Forward]
Balance, beginning of year	57,476		45,701		37,706
Additions	14,624	[1]	31,520	[1]	32,545	[1]
Amortization	(16,659)		(19,745)		(24,550)
Other	(365)
Balance, end of year	55,076		57,476		45,701
Cash payments made for contract acquisition	12,190		22,087		29,250
Accrued liabilities [Abstract]
Funds held for customers	43,829		35,475
Employee profit sharing/cash bonus and pension	23,783		34,109
Customer rebates	20,969		19,201
Contract acquisition costs due within one year	13,070		8,550
Interest	8,760		5,227
Restructuring due within one year (see Note 8)	5,946		6,435
Wages, including vacation	4,995		5,898
Other	28,746		29,139
Accrued liabilities	150,098		144,034
Supplemental cash flow disclosures [Abstract]
Interest paid	42,542		44,054		43,513
Income taxes paid	$ 60,861		$ 70,246		$ 56,060

[1] Contract acquisition costs are accrued upon contract execution. Cash payments made for contract acquisition costs were $12,190 in 2011 $22,087 in 2010 and $29,250 in 2009.