Employee Benefit Plans (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Changes in the fair value of Level 3 assets
Transfers from Level 3 to Level 2 assets	$ 0
Commingled Global Fund Allocations
Changes in the fair value of Level 3 assets
Number of funds transferred from level 3 to level 2		1
Significant Unobservable Inputs (Level 3)
Changes in the fair value of Level 3 assets
Fair value of plan assets - beginning of year	13.2	193.4
Transfers from Level 3 to Level 2 assets		(105.6)
Realized gains		0.9
Unrealized gains (losses) relating to instruments still held at period end	0.2	0.3
Purchases		3.1
Sales	(3.3)	(78.9)
Fair value of plan assets - end of year	10.1	13.2
Significant Unobservable Inputs (Level 3) \| Global Equity Common Trust Funds
Changes in the fair value of Level 3 assets
Fair value of plan assets - beginning of year	6.8	29.0
Unrealized gains (losses) relating to instruments still held at period end	0.2	0.4
Purchases		3.1
Sales	(2.1)	(25.7)
Fair value of plan assets - end of year	4.9	6.8
Significant Unobservable Inputs (Level 3) \| Commingled Global Fund Allocations
Changes in the fair value of Level 3 assets
Fair value of plan assets - beginning of year		155.6
Transfers from Level 3 to Level 2 assets		(105.6)
Realized gains		0.9
Sales		(50.9)
Significant Unobservable Inputs (Level 3) \| Fixed Income Common Trust Funds
Changes in the fair value of Level 3 assets
Fair value of plan assets - beginning of year		1.4
Sales		(1.4)
Significant Unobservable Inputs (Level 3) \| Other
Changes in the fair value of Level 3 assets
Fair value of plan assets - beginning of year	6.4	7.4
Unrealized gains (losses) relating to instruments still held at period end		(0.1)
Sales	(1.2)	(0.9)
Fair value of plan assets - end of year	$ 5.2	$ 6.4

The increase in plan assets attributed to the purchase of additional investments.

No definition available.

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Period Type:	duration

- Definition

The decrease in plan assets attributed to the sale of investments.

+ References

No definition available.

+ Details

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- Definition

Represents the number of funds transferred from level 3 to level 2.

+ References

No definition available.

+ Details

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Namespace Prefix:	spw_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Actual return on plan assets, separately identifying the amount related to assets sold during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(iv)(02)(A)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(iv)(02)(A)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

+ Details

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- Definition

Actual return on plan assets, separately identifying the amount related to assets still held at the reporting date.

+ References

+ Details

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- Details

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- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Section 35

-Paragraph 50

-URI http://asc.fasb.org/extlink&oid=29635418&loc=d3e12355-114930

+ Details

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- Definition

Transfers in and out of Level 3. For example, transfers due to changes in the observability of significant inputs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(iv)(02)(C)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(iv)(02)(C)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

+ Details

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- Details

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- Details

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