The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Debt Obligations - Credit Facility Current Borrowings (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility	$ 952,517	$ 668,427
Credit facility available for revolving loans or issuing new letters of credit	407,600
Letters of Credit and Bank Guarantees
Line of Credit Facility [Line Items]
Letters of credit and bank guarantees	449,900
Letters of Credit and Bank Guarantees \| U.S. Dollar
Line of Credit Facility [Line Items]
Letters of credit and bank guarantees	242,300
Letters of Credit and Bank Guarantees \| Primarily Canadian and Australian Dollars
Line of Credit Facility [Line Items]
Letters of credit and bank guarantees	207,600
Borrowings under Credit Facility
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility	952,500
Borrowings under Credit Facility \| U.S. Dollar
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility	772,400
Borrowings under Credit Facility \| Canadian Dollars
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility	100,700
Borrowings under Credit Facility \| Australian Dollars
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility	$ 79,400