Fair Value of Financial Instruments (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Series A senior notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	$ 0	$ 75,000
Fair Value	0	76,491
Series B senior notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	100,000	100,000
Fair Value	107,704	105,041
Series C senior notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	25,000	25,000
Fair Value	24,822	24,421
Revolving credit facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	191,919	153,600
Fair Value	186,590	152,974
United States term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	190,000	192,000
Fair Value	183,869	189,972
Canadian term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	21,983	24,989
Fair Value	21,226	24,651
Australia term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	89,443	0
Fair Value	88,299	0
Other debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	7,849	8,275
Fair Value	$ 7,775	$ 8,318