Supplemental balance sheet information (available-for-sale securities) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2014		Dec. 31, 2013
Available-for-sale securities [Line Items]
Cost	$ 14,507		$ 87,125
Gross unrealized gains	0		0
Gross unrealized losses	(211)		(343)
Fair value	14,296		86,782
Expected maturities of available-for-sale securities
Due in one year or less	4,954
Due in two to five years	6,502
Due in six to ten years	2,840
Total available-for-sale securities	14,296
Cash equivalents [Member] | Money market securities [Member] | Domestic
Available-for-sale securities [Line Items]
Cost	2,996		70,001
Gross unrealized gains	0		0
Gross unrealized losses	0		0
Fair value	2,996		70,001
Funds held for customers [Member]
Available-for-sale securities [Line Items]
Cost			15,079	[1]
Gross unrealized gains			0	[1]
Gross unrealized losses			(343)	[1]
Fair value			14,736	[1]
Cash	30,204		27,689
Funds held for customers [Member] | Canadian and provincial government securities [Member]
Available-for-sale securities [Line Items]
Cost	9,553	[2]	9,901
Gross unrealized gains	0	[2]	0
Gross unrealized losses	(211)	[2]	(343)
Fair value	9,342	[2]	9,558
Funds held for customers [Member] | Canadian guaranteed investment certificate [Member]
Available-for-sale securities [Line Items]
Cost			5,178
Gross unrealized gains			0
Gross unrealized losses			0
Fair value			5,178
Other current assets [Member] | Money market securities [Member] | Canadian
Available-for-sale securities [Line Items]
Cost	1,958		2,045
Gross unrealized gains	0		0
Gross unrealized losses	0		0
Fair value	$ 1,958		$ 2,045

[1] Funds held for customers, as reported on the consolidated balance sheet as of December 31, 2013, also included cash of $27,689.

[2] Funds held for customers, as reported on the consolidated balance sheet as of September 30, 2014, also included cash of $30,204.