Company's Debt Maturities on Calendar Year Basis (Parenthetical) (Detail) - USD ($) $ in Thousands		Mar. 14, 2018	Feb. 22, 2018	Dec. 31, 2017	Oct. 27, 2017	Aug. 02, 2017	Jun. 30, 2017	Dec. 31, 2016	Jul. 31, 2016	Jun. 30, 2016	Dec. 31, 2015	Mar. 18, 2013	Nov. 29, 2012
Debt Instrument [Line Items]
Principal amount of long term debt					$ 240,700		$ 0
Long-term debt, including current portion, Carrying Amount	[1]			$ 800,842				$ 1,254,160
Subsequent Event
Debt Instrument [Line Items]
Aggregate amount of term loan facility			$ 110
Convertible Notes | 1.50% Senior Subordinated Notes Due March 15, 2018
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage				1.50%				1.50%			1.50%	1.50%
Debt instrument, par value of notes repurchased				$ 58,900				$ 104,900	$ 53,200	$ 51,700
Principal amount of long term debt				236,200								$ 400,000
Long-term debt, including current portion, Carrying Amount	[2]			233,898				277,518
Convertible Notes | 1.50% Senior Subordinated Notes Due March 15, 2018 | Subsequent Event
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage		1.50%	1.50%
Principal amount of long term debt			$ 125,000
Convertible Notes | Scenario, Plan | 5.75% Senior Subordinated Notes Due August 2023 | Subsequent Event
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage			5.75%
Principal amount of long term debt			$ 125,000
Convertible Notes | FY 2016 and FY 2017 | 1.50% Senior Subordinated Notes Due March 15, 2018
Debt Instrument [Line Items]
Debt instrument, par value of notes repurchased				163,800
Second Delayed Draw Term Loan | Subsequent Event
Debt Instrument [Line Items]
Aggregate amount of term loan facility		$ 110,000
Variable Funding Notes
Debt Instrument [Line Items]
Principal amount of long term debt				100,000									$ 100,000
Long-term debt, including current portion, Carrying Amount	[3]			91,363				$ 100,000
2017 Senior Secured Term Loan
Debt Instrument [Line Items]
Principal amount of long term debt				82,800	$ 57,800	$ 300,000
Long-term debt, including current portion, Carrying Amount	[4]			$ 74,813

[1] Carrying amounts include aggregate unamortized debt discount and debt issuance costs.

[2] During FY 2016, the Company repurchased a total of $104.9 million par value (of which $51.7 million and $53.2 million were purchased in June 2016 and July 2016, respectively) of the 1.50% Convertible Notes. During FY 2017, the Company repurchased a total of $58.9 million par value of the 1.50% Convertible Notes. See below for further details. On February 22, 2018, the Company exchanged $125 million of aggregate principal amount of 1.50% Convertible Notes for $125 million of aggregate principal amount of 5.75% Convertible Notes, and on March 14, 2018, the Company drew down $110 million under the Second Delayed Draw Term Loan and used those proceeds, along with cash on hand, to make a payment to the trustee under the indenture governing the 1.50% Convertible Notes to repay the remaining 1.50% Convertible Notes at maturity on March 15, 2018.

[3] On August 18, 2017, the Company entered into an amendment of its Variable Funding Note which extended the anticipated repayment date for the Variable Funding Notes from January 2018 to January 2020. See below for further details

[4] On August 2, 2017, the Company entered into the DB Credit Agreement for an aggregate principal amount of $300 million. See below for further details.