Other Credit Arrangements - Additional Information (Detail) (USD $)	1 Months Ended
	Dec. 31, 2014	Jan. 31, 2015 Entity
Debt Disclosure [Line Items]
Borrowing agreements, number of financial institutions		2
Demand letter of credit facilities
Debt Disclosure [Line Items]
Borrowing agreements with financial institutions		155,000,000
Trade Letter of Credit
Debt Disclosure [Line Items]
Outstanding borrowings		13,700,000
Asset Based Credit Facility
Debt Disclosure [Line Items]
Line of credit facility, expiration period	5 years
Borrowing agreements with financial institutions	400,000,000
Unsecured Revolving Credit Facility
Debt Disclosure [Line Items]
Borrowing agreements with financial institutions		150,000,000
Letters of credit outstanding amount		8,100,000
Borrowings		0