Postretirement Benefit Plans (Details 9) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Assets:
Total Assets	$ 2,107.4	$ 3,290.6
Postretirement Benefit Plans [Member]
Assets:
Total Assets	120.0	240.1
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	120.0
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	9.4
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - equity [Member]
Assets:
Total Assets	37.7
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Funds [Member]
Assets:
Total Assets	22.1
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	50.8
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Assets:
Total Assets	0
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Common collective funds - equity [Member]
Assets:
Total Assets	0
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | International Equity Funds [Member]
Assets:
Total Assets	0
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	0
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Assets:
Total Assets	120.0
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	9.4
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Common collective funds - equity [Member]
Assets:
Total Assets	37.7
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | International Equity Funds [Member]
Assets:
Total Assets	22.1
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	50.8
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Assets:
Total Assets	0
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Common collective funds - equity [Member]
Assets:
Total Assets	0
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | International Equity Funds [Member]
Assets:
Total Assets	0
Postretirement Benefit Plans [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	$ 0