Debt (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Feb. 27, 2015
Debt Instrument [Line Items]
Write off of deferred debt issuance cost	$ 500,000
Line of credit facility, additional borrowing capacity	500,000,000
Debt instrument, interest, additional interest above eurodollar rate	1.00%
Derivative, fixed interest rate	2.26%
Debt instrument, interest rate at period end	2.46%
Line of credit facility, remaining borrowing capacity	1,100,000,000
Current portion of long-term debt	20,000,000		68,750,000
Long-term debt	385,000,000		136,250,000
Contract notional amount	245,650,000		261,325,000
Long-term line of credit	405,000,000	[1]	205,000,000	[1]
Letters of credit outstanding	9,300,000
Federal Funds rate
Debt Instrument [Line Items]
Debt instrument, interest, additional interest above federal fund rate	0.50%
Euro Dollar rate | Federal Funds rate
Debt Instrument [Line Items]
Minimum applicable margin rate	0.125%
Maximum applicable margin rate	0.50%
Revolving credit facility
Debt Instrument [Line Items]
Debt issuance cost	4,600,000
Term loan
Debt Instrument [Line Items]
Debt instrument, maturity duration	5 years
Line of credit facility, maximum borrowing capacity	400,000,000
Line of credit facility, frequency of payments in quarterly installments	16
Interest rate at period end	1.42%
Debt instrument, interest base rate	0.17%
Debt instrument, interest, additional interest above base rate	1.25%
Long-term line of credit	400,000,000	[2]	144,375,000	[2]
Revolver
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	1,100,000,000
Long-term line of credit	0	[2],[3]	55,625,000	[2],[3]
Revolver | Letter of credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	40,000,000
Connecticut Economic Development Program
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	5,000,000
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
Debt instrument, forgiveness period under the terms of the loan	5 years
Interest Rate Contract
Debt Instrument [Line Items]
Derivative, fixed interest rate	2.26%
Contract notional amount	200,000,000
Euro Dollar rate
Debt Instrument [Line Items]
Minimum applicable margin rate	1.125%
Maximum applicable margin rate	1.50%
Other liabilities
Debt Instrument [Line Items]
Interest rate derivative hedge, negative fair value	2,900,000		6,500,000
Subsequent event | Interest Rate Contract
Debt Instrument [Line Items]
Derivative, fixed interest rate					1.60%
Contract notional amount					$ 200,000,000.0

[1] As of December 31, 2014, $20.0 million of debt was classified as short term and $385.0 million was classified as long term on the Consolidated Balance Sheets.

[2] The contractual annual interest rate as of December 31, 2014 on the term loan was 1.42%, which consisted of a floating Eurodollar base rate of 0.17% plus a margin of 1.25%. However, the Company has an interest rate swap contract which converts the floating Eurodollar base rate to a 2.26% fixed base rate on the first $200.0 million of Company borrowings (see below). As a result, the Company’s weighted-average annual interest rate on the $400.0 million of outstanding debt under the 2014 Credit Facility as of December 31, 2014, including the margin, was approximately 2.46%.

[3] The Company had approximately $1.1 billion of available borrowing capacity on the revolver (not including the expansion feature) as of December 31, 2014.