Long-Term Debt (Tax-Exempt Bond Financings) (Detail) - Tax-Exempt Bonds [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Outstanding balance of bonds	$ 15,930	$ 95,430
Outstanding standby letters of credit	$ 16,126
West Valley Bond
Debt Instrument [Line Items]
Type of interest rate	Variable
Maturity date of bond	Aug. 01, 2018
Outstanding balance of bonds		15,500
Lemay Washington Bond [Member]
Debt Instrument [Line Items]
Type of interest rate	Variable
Interest rate on bond at December 31, 2018	1.79%
Maturity date of bond	Apr. 01, 2033
Outstanding balance of bonds	$ 15,930	15,930
Outstanding standby letters of credit	$ 16,126
PA IRB Facility Bond [Member]
Debt Instrument [Line Items]
Type of interest rate	Variable
Maturity date of bond	Nov. 01, 2028
Outstanding balance of bonds		35,000
TX IRB Facility Bond [Member]
Debt Instrument [Line Items]
Type of interest rate	Variable
Maturity date of bond	Apr. 01, 2022
Outstanding balance of bonds		24,000
2009 Seneca IRB Facility Bond [Member]
Debt Instrument [Line Items]
Type of interest rate	Variable
Maturity date of bond	Dec. 31, 2039
Outstanding balance of bonds		$ 5,000

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-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://www.xbrl.org/2003/role/presentationRef
-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

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-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

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- Definition

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

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- Definition

Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

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- Definition

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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No definition available.

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- Definition

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

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- Definition

The amount of outstanding standby letters of credit as of the reporting date.

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