Debt (Detail) - Borrowings - USD ($)		6 Months Ended	12 Months Ended
		Jun. 30, 2015	Dec. 31, 2012	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term line of credit	[1]	$ 715,000,000		$ 405,000,000
Debt instrument, interest, additional interest above base rate		1.38%
Notional amount of interest rate derivatives		$ 711,000,000		245,650,000
Line of credit facility, remaining borrowing capacity		776,000,000
Line of credit facility, maximum borrowing capacity		$ 1,500,000,000.0
Debt instrument, effective percentage		3.11%
Minimum
Debt Instrument [Line Items]
Floating eurodollar based rate		0.18%
Maximum
Debt Instrument [Line Items]
Floating eurodollar based rate		0.28%
Term loans
Debt Instrument [Line Items]
Long-term line of credit	[2]	$ 390,000,000		400,000,000
Line of credit facility, maximum borrowing capacity		$ 400,000,000
Term loans | Minimum
Debt Instrument [Line Items]
Contractual annualized interest rate	[2]	1.56%
Term loans | Maximum
Debt Instrument [Line Items]
Contractual annualized interest rate	[2]	1.66%
Revolver loans
Debt Instrument [Line Items]
Long-term line of credit	[2],[3]	$ 320,000,000		0
Line of credit facility, maximum borrowing capacity		$ 1,100,000,000.0
Revolver loans | Minimum
Debt Instrument [Line Items]
Contractual annualized interest rate		1.56%
Revolver loans | Maximum
Debt Instrument [Line Items]
Contractual annualized interest rate		1.66%
Other
Debt Instrument [Line Items]
Long-term line of credit	[4]	$ 5,000,000		$ 5,000,000
Connecticut Economic Development Program
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 5,000,000.0
Debt instrument, fixed interest rate			3.00%
Debt instrument, maturity period			10 years
Debt instrument, period principal payments are deferred			5 years
Line of credit facility, decrease, forgiveness			$ 2,500,000.0
Debt instrument, forgiveness period under the terms of the loan			5 years
Interest rate swap
Debt Instrument [Line Items]
Notional amount of interest rate derivatives		$ 700,000,000

[1] The average annual effective rate on the Company's total debt outstanding as of June 30, 2015, including the effect of the swaps, was approximately 3.11%

[2] The contractual annualized interest rates as of June 30, 2015 on the term loan and the revolver ranged from 1.56% to 1.66%, which consisted of a floating eurodollar base rate ranging from 0.18% to 0.28% plus a margin of 1.38%. However, the Company has interest rate swap contracts which convert the floating eurodollar base rates to a fixed base rate on $700.0 million of Company borrowings (see below).

[3] The Company had $776.0 million of available borrowing capacity on the revolver (not including the expansion feature) as of June 30, 2015.

[4] Consists of a $5.0 million State of Connecticut economic development loan with a 3.0% fixed rate of interest. The loan was originated in 2012 and has a 10 years maturity. Principal payments are deferred for the first five years and the loan may be repaid at any point by the Company without penalty. The loan has a principal forgiveness provision in which up to $2.5 million of the loan may be forgiven if the Company meets certain employment targets during the first five years of the loan.