Segment Reporting - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2014 Segment	Mar. 31, 2013
Segment Reporting [Abstract]
Number of reporting segments	3
Number of operating segments	4
Accrued capital expenditures		$ 34.0
Cash payments for accrued capital expenditures outstanding	$ 8.3

The amount of total capital as defined in the regulations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47304-110998

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=7881181&loc=d3e65071-112826

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

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-Section 50

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-URI http://asc.fasb.org/extlink&oid=7881181&loc=d3e65071-112826

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 10

-Section 50

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-URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47080-110998

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