Employee Benefit Plans (Details 13) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Assets Category:
Fair value	$ 315.0		$ 302.8
NAV [Member]
Assets Category:
Fair value	309.2		294.6
Commingled Pools / Collective Trusts [Member] | U.S. Equity [Member]
Assets Category:
Fair value	78.0	[1]	100.1	[1]
Redemption Frequency (if currently eligible)	Daily	[2]	Daily	[2]
Redemption Notice Period	5 days	[2]	5 days	[2]
Commingled Pools / Collective Trusts [Member] | International Equity [Member]
Assets Category:
Fair value	47.3	[1]	70.8	[1]
Redemption Frequency (if currently eligible)	Daily	[1]	Daily	[1]
Redemption Notice Period	5 days	[1]	5 days	[1]
Commingled Pools / Collective Trusts [Member] | Fixed income [Member]
Assets Category:
Fair value	145.4	[3]	89.4	[3]
Redemption Frequency (if currently eligible)	Daily	[3]	Daily	[3]
Balanced pension trusts [Member] | International Equity [Member]
Assets Category:
Fair value	4.7	[4]	10.8	[4]
Redemption Frequency (if currently eligible)	Daily	[4]	Daily	[4]
Balanced pension trusts [Member] | Fixed income [Member]
Assets Category:
Fair value	14.2	[4]	7.2	[4]
Redemption Frequency (if currently eligible)	Daily	[4]	Daily	[4]
Pension Funds [Member] | International Equity [Member]
Assets Category:
Fair value	11.4	[5]	9.4	[5]
Redemption Frequency (if currently eligible)	Daily	[5]	Daily	[5]
Redemption Notice Period			7 days	[4]
Pension Funds [Member] | Fixed income [Member]
Assets Category:
Fair value	$ 8.2	[6]	$ 6.9	[6]
Redemption Frequency (if currently eligible)	Daily	[6]	Daily	[6]
Redemption Notice Period			7 days	[4]
Minimum [Member] | Commingled Pools / Collective Trusts [Member] | Fixed income [Member]
Assets Category:
Redemption Notice Period	5 days		5 days
Minimum [Member] | Balanced pension trusts [Member] | International Equity [Member]
Assets Category:
Redemption Notice Period	3 days		3 days
Minimum [Member] | Balanced pension trusts [Member] | Fixed income [Member]
Assets Category:
Redemption Notice Period	3 days		3 days
Minimum [Member] | Pension Funds [Member] | International Equity [Member]
Assets Category:
Redemption Notice Period	1 day
Minimum [Member] | Pension Funds [Member] | Fixed income [Member]
Assets Category:
Redemption Notice Period	1 day
Maximum [Member] | Commingled Pools / Collective Trusts [Member] | Fixed income [Member]
Assets Category:
Redemption Notice Period	15 days		15 days
Maximum [Member] | Balanced pension trusts [Member] | International Equity [Member]
Assets Category:
Redemption Notice Period	5 days		5 days
Maximum [Member] | Balanced pension trusts [Member] | Fixed income [Member]
Assets Category:
Redemption Notice Period	5 days		5 days
Maximum [Member] | Pension Funds [Member] | International Equity [Member]
Assets Category:
Redemption Notice Period	7 days
Maximum [Member] | Pension Funds [Member] | Fixed income [Member]
Assets Category:
Redemption Notice Period	7 days

[1] This category includes investments primarily in international equity securities that include large, mid and small capitalization companies in large developed markets as well as emerging markets equities.

[2] This category includes investments primarily in U.S. equity securities that include large, mid and small capitalization companies.

[3] This category includes investments in U.S. investment grade and high yield fixed income securities, international fixed income securities and emerging markets fixed income securities.

[4] The investment objectives of the fund are to provide long-term capital growth and income by investing primarily in a well-diversified, balanced portfolio of Canadian common stocks, bonds and money market securities. The fund also holds a portion of its assets in international equities.

[5] This category includes investments in international equity securities and aims to provide returns consistent with the markets in which it invests and provide broad exposure to countries around the world.

[6] This category includes investments in U.K. government index-linked securities (index-linked gilts) that have maturity periods of 5 years or longer and investment grade corporate bonds denominated in sterling.