Other Operating Income (Expense) - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Component Of Other Income And Expense [Abstract]
Insurance recoveries	$ 400,000us-gaap_InsuranceRecoveries	$ 8,800,000us-gaap_InsuranceRecoveries	$ 400,000us-gaap_InsuranceRecoveries	$ 800,000us-gaap_InsuranceRecoveries	$ 5,700,000us-gaap_InsuranceRecoveries	$ 2,200,000us-gaap_InsuranceRecoveries	$ 900,000us-gaap_InsuranceRecoveries	$ 600,000us-gaap_InsuranceRecoveries	$ 10,368,000us-gaap_InsuranceRecoveries	$ 9,427,000us-gaap_InsuranceRecoveries	$ 3,311,000us-gaap_InsuranceRecoveries
Proceeds from sale of certain real properties											$ 3,200,000

The amount recovered from insurance. These recoveries reduce costs and losses that are reported as a separate line item under operating expenses.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.3)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Name:	us-gaap_InsuranceRecoveries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration