DEBT - Additional Information (Detail) - USD ($)		1 Months Ended
	Apr. 30, 2015	Apr. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
$1.2 billion senior credit facility weighted average rate 1.47%, due in 2019
Debt Instrument [Line Items]
Maximum borrowing capacity of line of credit facility			$ 1,200,000,000.0
Revolving credit facility, amount committed to outstanding letters of credit			152,200,000	$ 162,900,000
Revolving credit facility, unused portion			685,200,000	$ 577,100,000
$250 million term loan 0.97%, due in 2015
Debt Instrument [Line Items]
Long-term debt, face amount			$ 250,000,000
Stated interest rate			0.97%
$175 million private placement notes 3.89%, due in 2017
Debt Instrument [Line Items]
Long-term debt, face amount			$ 175,000,000.0
Stated interest rate			3.89%
$125 million private placement notes 2.68%, due in 2019
Debt Instrument [Line Items]
Long-term debt, face amount			$ 125,000,000.0
Stated interest rate			2.68%
$225 million private placement notes 4.47%, due in 2020
Debt Instrument [Line Items]
Long-term debt, face amount			$ 225,000,000.0
Stated interest rate			4.47%
$125 million private placement notes 3.26%, due in 2022
Debt Instrument [Line Items]
Long-term debt, face amount			$ 125,000,000.0
Stated interest rate			3.26%
Long-term Debt [Member] | $250 million term loan 0.97%, due in 2015
Debt Instrument [Line Items]
Long-term debt, face amount			$ 250,000,000.0
Long-term Debt [Member] | $100 million private placement notes 5.64%, due in 2015
Debt Instrument [Line Items]
Repayments of Debt		$ 100,000,000
Senior Notes 2.67% Series A | Senior Notes
Debt Instrument [Line Items]
Long-term debt, face amount	$ 200,000,000	$ 200,000,000
Debt instrument, term	7 years
Stated interest rate	2.72%	2.72%
Senior Notes 2.74% Series B | Senior Notes
Debt Instrument [Line Items]
Long-term debt, face amount	$ 100,000,000	$ 100,000,000
Debt instrument, term	8 years
Stated interest rate	2.79%	2.79%