Debt (Summary of Debt) (Details) - USD ($) $ in Thousands		6 Months Ended
Dec. 21, 2016	Jun. 30, 2017	Dec. 31, 2016
Debt [Line Items]
Short-term debt		$ 14,110	$ 23,912
Long-term Debt, Total		814,313	595,706
Total debt		828,423	619,618
Current portion		16,618
Non-current portion		$ 797,695	595,706
Revolving Loan, In Canadian Dollars, Available until October 2021 [Member]
Debt [Line Items]
Long-term Debt			69,926
Weighted average interest rate		2.38%
Maturity date		Oct. 27, 2021
Revolving Loan, In US Dollars, Available until October 2021 [Member]
Debt [Line Items]
Long-term Debt			30,000
Weighted average interest rate		2.075%
Maturity date		Oct. 27, 2021
Delayed Draw Term Loan, In Canadian Dollars, Available until October 2021 [Member]
Debt [Line Items]
Long-term Debt		$ 184,113
Interest rate		2.35%
Maturity date		Oct. 27, 2021
Delayed Draw Term Loan, In US Dollars, Available until October 2021 [Member]
Debt [Line Items]
Long-term Debt		$ 148,250
Less: unamortized debt issue costs		$ (4,545)
Interest rate		2.551%
Maturity date		Oct. 27, 2021
5.375% Senior Unsecured Note, Due January 2025 [Member]
Debt [Line Items]
Long-term Debt		$ 500,000	500,000
Less: unamortized debt issue costs	$ (13,883)	$ (13,505)	$ (4,220)
Interest rate	5.375%	5.375%	5.375%
Maturity date	Jan. 15, 2025	Jan. 15, 2025

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 210
-Section S99
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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Contractual interest rate for funds borrowed, under the debt agreement.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Represents the aggregate of total long-term debt, including current maturities and short-term debt.

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Weighted average interest rate of debt outstanding.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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