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Debt instrument final payment fee percentage.

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Debt Instrument, Maturity, Month and Year

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Debt instrument origination fee percentage.

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Debt instrument prepayment after twenty four months fee percent.

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Debt instrument prepayment fee percentage made within twelve months.

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Debt instrument repurchase price percentage.

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Line of credit facility additional tranche may be increased.

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Outstanding long term debt balance.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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The price per share of the conversion feature embedded in the debt instrument.

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Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

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The number of equity instruments that the holder of the debt instrument would receive if the debt was converted to equity.

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The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

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Face (par) amount of debt instrument at time of issuance.

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Amount of the fee that accompanies borrowing money under the debt instrument.

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Description of the frequency of periodic payments (monthly, quarterly, annual).

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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The cap rate on a price risk derivative such as a cap or collar. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract.

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The strike price on the price risk option contract such as a put option or a call option.

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Amount of the cost of borrowed funds accounted for as interest expense for debt.

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Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

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Date the first payment under the line of credit must be paid, in CCYY-MM-DD format.

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Description of the frequency of periodic payments, which may be presented in a variety of ways (for example, monthly, quarterly, annually).

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Amount of the required periodic payment applied to principal.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

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The cash inflow from the issuance of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

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The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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Indebtedness - Additional Information (Detail)		1 Months Ended	12 Months Ended
Indebtedness - Additional Information (Detail)	Nov. 14, 2017 USD ($) shares $ / shares	Jul. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) Loan $ / shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Proceeds for issuance of notes allocated to equity			$ 570,000,000
Amount paid for capped calls transactions			50,901,000
Repayment of outstanding balance			15,109,000	$ 7,603,000	$ 2,598,000
Revolving line-of-credit outstanding balance			601,328,000
Total indebtedness of unpaid principal balance			$ 1,300,000
Sale of Airport Facility date			2018-01
Long-term debt			$ 424,876,000	6,042,000
July 2017 Term Loan [Member]
Debt Instrument [Line Items]
Debt issuance costs			1,100,000
Net proceeds from issuance of debt			29,100,000
Long-term debt			30,000,000
June 2015 Term Loan [Member]
Debt Instrument [Line Items]
Repayment of outstanding balance			9,200,000
Long-term debt				15,000,000
Mortgage Loan One [Member]
Debt Instrument [Line Items]
Revolving line-of-credit outstanding balance			800,000
Mortgage Loan Two [Member]
Debt Instrument [Line Items]
Revolving line-of-credit outstanding balance			500,000
Convertible Debt, The Term Loan, The Revolver and The Mortgage Loans [Member]
Debt Instrument [Line Items]
Current portion of long-term debt			6,200,000
Long-term debt			424,900,000
Interest expense related to debt facilities			5,800,000	$ 1,900,000	$ 1,300,000
Maximum [Member] \| Revolving Loan [Member]
Debt Instrument [Line Items]
Revolving line-of-credit outstanding balance			100,000
2024 Convertible Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 570,000,000		$ 570,000,000
Debt instrument, maturity date	Nov. 15, 2024
Debt instrument, interest rate per annum	1.50%
Debt instrument, payment frequency			The 2024 Notes were issued at face value and bear interest at the rate of 1.50% per annum, payable semi-annually in cash on each May 15 and November 15, commencing on May 15, 2018.
Debt instrument, conversion rate	0.013621
Debt instrument, conversion price \| $ / shares	$ 73.42		$ 73.42
Debt issuance costs	$ 14,800,000
Proceeds for issuance of notes allocated to equity	161,100,000
Offering costs	4,200,000
Debt discount and issuance costs on notes	$ 10,600,000
Effective interest rate percentage	6.90%
Capped calls strike price \| $ / shares	73.42
Capped calls cap price \| $ / shares	104.88
Amount paid for capped calls transactions	$ 50,900,000
2024 Convertible Notes [Member] \| Fundamental Change [Member]
Debt Instrument [Line Items]
Debt instrument, repurchase price percentage	100.00%
2024 Convertible Notes [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Percentage of additional interest expenses from fail to register notes after 180 days and 380 days after issuance date	0.25%
2024 Convertible Notes [Member] \| Minimum [Member] \| Beneficial Owner [Member] \| Fundamental Change [Member]
Debt Instrument [Line Items]
Voting percentage	50.00%
2024 Convertible Notes [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Percentage of additional interest expenses from fail to register notes after 180 days and 380 days after issuance date	0.50%
2024 Convertible Notes [Member] \| Common Stock [Member]
Debt Instrument [Line Items]
Debt instrument, convertible into shares \| shares	7,763,552
MidCap Financial Amended and Restated Credit and Security Agreement [Member] \| July 2017 Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate per annum		6.25%
Current borrowing capacity		$ 60,000,000
Variable interest rate description		one-month London Interbank Offered Rate
Origination fee, percentage		0.50%
Final payment fee, percentage		2.00%
Monthly principal payments commencement date		Jul. 01, 2018
Periodic principal payment frequency		monthly
Monthly principal payments		$ 800,000
Credit facility maturity date		2021-07
Debt instrument prepayment fee percent within twelve months			3.00%
Debt instrument prepayment fee percent on or after twelve months and within twenty four months			2.00%
Debt instrument prepayment fee percent on or after twenty four months			1.00%
Percentage of minimum amount of cash and/or cash equivalents on outstanding principal amounts			75.00%
Midcap Financial Revolving Credit and Security Agreement [Member] \| Revolving Loan [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate per annum		3.95%
Current borrowing capacity		$ 40,000,000
Variable interest rate description			one-month LIBOR
Origination fee, percentage		0.50%
Credit facility maturity date		2021-07
Percentage of minimum amount of cash and/or cash equivalents on outstanding principal amounts			75.00%
Line of credit facility additional tranche that may be increased		$ 20,000,000
Origination fee		$ 200,000
Mortgage Loans [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate per annum			4.75%
Credit facility maturity date			2027-02
Number of mortgage loans outstanding \| Loan			2