Commitments and Contingencies (Supply Agreements) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014 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	10
Ammonia [Member]
Unrecorded Unconditional Purchase Obligation[Line Items]
Annual commitments under unrecorded unconditional purchase obligations	1.0
Air Products [Member] | Bulk Gases [Member]
Unrecorded Unconditional Purchase Obligation[Line Items]
Supply agreement expiration date	2017
Annual commitments under unrecorded unconditional purchase obligations	52.0
Linde AG [Member] | Bulk Gases [Member]
Unrecorded Unconditional Purchase Obligation[Line Items]
Supply agreement expiration date	2019
Annual commitments under unrecorded unconditional purchase obligations	45.0
Other Producers [Member] | Bulk Gases [Member]
Unrecorded Unconditional Purchase Obligation[Line Items]
Supply agreement expiration date	2024
Annual commitments under unrecorded unconditional purchase obligations	$ 29.0