Fair Value of Financial Instruments (Details 2) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value	$ 597,334	$ 578,864
Fair value	596,576	581,868
Series A Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value	75,000	75,000
Fair value	74,983	76,491
Series B Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value	100,000	100,000
Fair value	107,893	105,041
Series C Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value	25,000	25,000
Fair value	24,722	24,421
Revolving Credit Facility [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value	85,655	153,600
Fair value	84,028	152,974
United States Term Loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value	195,000	192,000
Fair value	189,737	189,972
Canadian Term Loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value	21,940	24,989
Fair value	21,317	24,651
Australian Term Loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value	86,900	0
Fair value	86,067	0
Other Debt Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value	7,839	8,275
Fair value	$ 7,829	$ 8,318