Employee Benefits Schedule of fair value of financial assets for pension and postretirement benefits (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 672.0	$ 548.4
Corporate bonds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1.7	1.9
U.S. government securities [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1.6	2.0
Fixed income registered investment companies [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	110.7	79.2
Inflation protection registered investment companies [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	29.4	25.5
Domestic equity registered investment companies [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2.0	1.9
Cash equivalent commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3.5	20.8
Domestic equity index commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	256.2	185.9
Foreign equity growth commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	42.9	37.3
Foreign equity index commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	76.0	60.1
Corporate debt commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	72.1	72.8
Inflation protection commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	28.8	24.5
Foreign equity growth 103-12 investment entities [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	47.1	36.5
Level 1 [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	142.1	106.6
Level 1 [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Level 1 [Member] | U.S. government securities [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Level 1 [Member] | Fixed income registered investment companies [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	110.7	79.2
Level 1 [Member] | Inflation protection registered investment companies [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	29.4	25.5
Level 1 [Member] | Domestic equity registered investment companies [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2.0	1.9
Level 1 [Member] | Cash equivalent commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Level 1 [Member] | Domestic equity index commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Level 1 [Member] | Foreign equity growth commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Level 1 [Member] | Foreign equity index commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Level 1 [Member] | Corporate debt commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Level 1 [Member] | Inflation protection commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Level 1 [Member] | Foreign equity growth 103-12 investment entities [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Level 2 [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	529.9	441.8
Level 2 [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1.7	1.9
Level 2 [Member] | U.S. government securities [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1.6	2.0
Level 2 [Member] | Fixed income registered investment companies [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Level 2 [Member] | Inflation protection registered investment companies [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Level 2 [Member] | Domestic equity registered investment companies [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Level 2 [Member] | Cash equivalent commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3.5	20.8
Level 2 [Member] | Domestic equity index commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	256.2	185.9
Level 2 [Member] | Foreign equity growth commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	42.9	37.3
Level 2 [Member] | Foreign equity index commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	76.0	60.1
Level 2 [Member] | Corporate debt commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	72.1	72.8
Level 2 [Member] | Inflation protection commingled funds [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	28.8	24.5
Level 2 [Member] | Foreign equity growth 103-12 investment entities [Member]
Defined Benefit Plan Disclosure Fair Value [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 47.1	$ 36.5