Amount of derivative notional contract settled at previously determined date.

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- Definition

Represents the percentage of the entity's share in the expected natural gas purchase which was hedged by swap agreement.

+ References

No definition available.

+ Details

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- Definition

Percentage of the entity's share in required natural gas purchases hedge, through December 2019

+ References

No definition available.

+ Details

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- Definition

Percentage of the entity's share in required natural gas purchases hedge, through December 2020

+ References

No definition available.

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- Definition

Interest rate that will be received or paid upon the exercise of the interest rate swaption contract after the addition of applicable margin in the fixed rate of the swap.

+ References

No definition available.

+ Details

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- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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- Definition

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.

+ References

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
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Balance Type:	credit
Period Type:	instant

- Definition

The percentage points added to the reference rate to compute the variable rate on the interest rate derivative.

+ References

No definition available.

+ Details

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- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Nominal energy measure used to calculate payments on a derivative instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:energyItemType
Balance Type:	na
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- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5579245-113959

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- Definition

Fixed interest rate that will be received or paid upon exercise of the interest rate swaption contract.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Foreign exchange rate used to translate amounts denominated in functional currency to reporting currency.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6897108&loc=SL6897125-166521

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Accounting for derivative instruments and hedging activities (Details) kJ in Millions, CAD in Millions, $ in Millions	1 Months Ended			6 Months Ended	12 Months Ended
	Jul. 31, 2017 CAD MMBTU	Dec. 31, 2016 USD ($) MMBTU	Jun. 30, 2014 kJ	Jun. 30, 2017 CAD MMBTU item	Dec. 31, 2016 USD ($) MMBTU	Jul. 31, 2017 USD ($)	Jun. 30, 2017 USD ($) item	Jun. 19, 2017 CAD	Mar. 31, 2017 CAD
Derivative instruments
Number of derivative contracts designated as cash flow hedges \| item				1			1
Senior secured term loan facility
Derivative instruments
Minimum fixed interest rate (as a percent)				5.25%			5.25%
Piedmont term loan, due 2018
Derivative instruments
Remaining aggregate principal amount \| $		$ 56.6			$ 56.6		$ 56.6
Applicable margin (as a percent)				3.75%
Adjusted Eurodollar Rate \| Senior secured term loan facility
Derivative instruments
Minimum fixed interest rate (as a percent)				1.00%			1.00%
Piedmont Project \| LIBOR \| Piedmont term loan, due 2018
Derivative instruments
Applicable margin of derivative (as a percent)				3.75%			3.75%
Gas purchase agreements \| Morris Project
Derivative instruments
Notional amount, energy (in gigajoules: Ontario, in Mmbtu: Orlando and Morris) \| MMBTU				120,000
Natural gas swaps
Derivative instruments
Notional amount, energy (in gigajoules: Ontario, in Mmbtu: Orlando and Morris) \| MMBTU				6,000,000	4,900,000
Natural gas swaps \| Ontario project
Derivative instruments
Notional amount, energy (in gigajoules: Ontario, in Mmbtu: Orlando and Morris) \| kJ			2.9
Natural gas swaps \| Kenilworth project
Derivative instruments
Notional amount, energy (in gigajoules: Ontario, in Mmbtu: Orlando and Morris) \| MMBTU		800,000
Natural gas swaps \| Orlando project
Derivative instruments
Notional amount, energy (in gigajoules: Ontario, in Mmbtu: Orlando and Morris) \| MMBTU	6,200,000			3,700,000
Percentage of the entity's share in required natural gas purchases hedge				90.00%
Percentage of the entity's share in required natural gas purchases hedge, through December 2019	90.00%
Percentage of the entity's share in required natural gas purchases hedge, through December 2020	50.00%
Interest rate swaps
Derivative instruments
Notional amount \| $		$ 506.9			$ 506.9		$ 458.4
Interest rate swaps \| APLP Holdings \| Adjusted Eurodollar Rate \| Senior secured term loan facility
Derivative instruments
Applicable margin of derivative (as a percent)				4.25%			4.25%
Interest rate swaps \| Swaption interest rate until February 15, 2019 \| Cadillac Project
Derivative instruments
Swaption interest rate (as a percent)				6.10%			6.10%
Interest rate swaps \| Derivative Swaption Interest Rate Until August 2018 [Member] \| Piedmont Project
Derivative instruments
Applicable margin (as a percent)				4.00%
Swaption interest rate (as a percent)				4.47%			4.47%
Swaption all in one interest rate (as a percent)				8.47%			8.47%
Interest rate swaps \| Swaption interest rate from February 16, 2019 to February 15, 2023 \| Cadillac Project
Derivative instruments
Swaption interest rate (as a percent)				6.30%			6.30%
Interest rate swaps \| Swaption interest rate after February 15, 2023 \| Cadillac Project
Derivative instruments
Swaption interest rate (as a percent)				6.40%			6.40%
Interest rate swaps \| Swaption interest rate From August, 2018 to November, 2030 \| Piedmont Project
Derivative instruments
Swaption interest rate (as a percent)				4.47%			4.47%
Foreign currency forward contracts
Derivative instruments
Notional amount \| CAD				CAD 20.0
Foreign Exchange Forward Rate 1.3381 \| Derivative instruments not designated as cash flow hedges
Derivative instruments
Notional amount \| CAD									CAD 10.0
Forward contract settled \| CAD								CAD 10.0
Foreign currency exchange rate									1.3381
Foreign Exchange Forward Rate 1.2943 \| Derivative instruments not designated as cash flow hedges \| Subsequent event
Derivative instruments
Notional amount \| $						$ 10.0
Foreign currency exchange rate	1.2943					1.2943
Foreign Exchange Forward Rate 1.2481 \| Derivative instruments not designated as cash flow hedges
Derivative instruments
Notional amount \| CAD	CAD 3.3
Foreign currency exchange rate	1.2481					1.2481