Long-Term Debt - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended
	May 02, 2013	Sep. 28, 2013
Unsecured private placement notes
Line of Credit Facility [Line Items]
Interest rate spread on notes (in percent)		0.60%
Long-term debt, notes		$ 75,000
Long-term debt maturities		Jun. 30, 2015
Outstanding balance, notes		75,000
Interest rate on notes (in percent)		0.87%
Debt Instrument, description of variable rate basis		The notes bear interest at 0.60% over LIBOR
Debt instrument, frequency of periodic payment		The notes do not require principal payments until maturity
Unsecured Debt [Member]
Line of Credit Facility [Line Items]
Long-term debt, notes		100,000
Outstanding balance, notes		100,000
Interest rate on notes (in percent)		3.81%
Unsecured revolving credit facility
Line of Credit Facility [Line Items]
Revolving credit facility		250,000
Debt facility expiration date		Mar. 07, 2017
Interest rate spread on notes (in percent)		1.25%
Borrowings outstanding under the revolving credit facility		6,600
Letters of credit sub-limit		50,000
Outstanding letters of credit		636
Interest rate (in percent)		2.12%
Fee payment on unused daily balances (in percent)		0.20%
Debt amendment date	Apr. 12, 2013
Effective date of debt amendment, latest	Jun. 30, 2015
Line of credit facility, interest rate description		Borrowings in U.S. dollars under this credit facility generally bear interest at the adjusted London Interbank Offered Rate ("LIBOR") for specified interest periods plus a margin, which can range from 1.00% to 2.00%, depending on our consolidated leverage ratio. Additionally, we have access to a swingline facility under this line of credit as well as alternative base rate borrowings that are priced based on an agreed upon baseline rate plus a spread determined by the same consolidated leverage ratio.
Secured Revolving Credit Facility
Line of Credit Facility [Line Items]
Revolving credit facility		50,000
Debt facility expiration date		Sep. 27, 2016
Interest rate spread on notes (in percent)		0.75%
Interest rate on letters of credit outstanding (in percent)		0.80%
Borrowings outstanding under the revolving credit facility		0
Outstanding letters of credit		26,225
Fee payment on unused daily balances (in percent)		0.26%
Line of credit facility, interest rate description		We pay interest at a rate per annum equal to a margin of 0.75%, plus LIBOR.
Minimum | Unsecured revolving credit facility
Line of Credit Facility [Line Items]
Interest rate spread on notes (in percent)		1.00%
Maximum | Unsecured revolving credit facility
Line of Credit Facility [Line Items]
Interest rate spread on notes (in percent)		2.00%
Unsecured Senior Notes 1 [Member] | Unsecured Debt [Member]
Line of Credit Facility [Line Items]
Long-term debt, notes		50,000
Interest rate on fixed rate notes (in percent)		3.73%
Long-term debt maturities		Apr. 15, 2023
Unsecured Senior Notes 2 [Member] | Unsecured Debt [Member]
Line of Credit Facility [Line Items]
Long-term debt, notes		$ 50,000
Interest rate on fixed rate notes (in percent)		3.88%
Long-term debt maturities		Apr. 15, 2025