Commitments and Contingencies (Supply Agreements) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013 suppliers
Liquid Carbon Dioxide [Member]
Unrecorded Unconditional Purchase Obligation[Line Items]
Supply Agreement Expiration Date	2044
Annual commitments under unrecorded unconditional purchase obligations	$ 22.0
Number of suppliers	15
Ammonia [Member]
Unrecorded Unconditional Purchase Obligation[Line Items]
Annual commitments under unrecorded unconditional purchase obligations	1.9
Air Products [Member] | Bulk Gases [Member]
Unrecorded Unconditional Purchase Obligation[Line Items]
Supply Agreement Expiration Date	2017
Annual commitments under unrecorded unconditional purchase obligations	51.0
Linde AG [Member] | Bulk Gases [Member]
Unrecorded Unconditional Purchase Obligation[Line Items]
Supply Agreement Expiration Date	2019
Annual commitments under unrecorded unconditional purchase obligations	44.0
Other Producers [Member] | Bulk Gases [Member]
Unrecorded Unconditional Purchase Obligation[Line Items]
Supply Agreement Expiration Date	2024
Annual commitments under unrecorded unconditional purchase obligations	$ 26.0