Represents term of option to extend credit facility after the maturity date specified in the agreement.

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The effective borrowing margin percentage rate, to which the higher of two alternative variable rates is added.

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Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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No definition available.

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

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The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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No definition available.

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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.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

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No definition available.

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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 of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Weighted average interest rate of long-term debt outstanding.

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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

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General - Long Term Debt and Capital Lease Obligation (Details) - USD ($) $ in Thousands					6 Months Ended
	Mar. 14, 2017	Jan. 10, 2017	Sep. 30, 2014	Jul. 23, 2014	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Jun. 27, 2016
Long-term Debt and Capital Lease Obligations
Proceeds from issuance of debt					$ 200,000	$ 225,000
Debt disclosures
Capital lease obligations					24,900		$ 26,000
Deferred loan issuance cost					1,200		1,400
Revolving Loan borrowings
Debt disclosures
Revolving borrowings outstanding					0
Letter of Credit
Debt disclosures
Letters of credit outstanding					27,000		33,700
Term Loan
Long-term Debt, Fiscal Year Maturity
2017					412,500
2018					25,000
2019					168,700
2014 Credit Facility
Long-term Debt and Capital Lease Obligations
Maximum borrowing capacity				$ 500,000
Term of option to extend credit facility				1 year
Debt disclosures
Available borrowing capacity					$ 223,000
2014 Credit Facility \| Revolving Loan borrowings
Long-term Debt and Capital Lease Obligations
Maximum borrowing capacity				$ 250,000
Debt disclosures
Revolving borrowings outstanding							$ 175,000
2014 Credit Facility \| Letter of Credit
Long-term Debt and Capital Lease Obligations
Maximum borrowing capacity				70,000
2014 Credit Facility \| Letter of Credit \| Minimum
Long-term Debt and Capital Lease Obligations
Stated interest rate (as a percent)					1.50%
Commitment commission (as a percent)					0.20%
2014 Credit Facility \| Letter of Credit \| Maximum
Long-term Debt and Capital Lease Obligations
Stated interest rate (as a percent)					2.00%
Commitment commission (as a percent)					0.35%
2014 Credit Facility \| Term Loan
Long-term Debt and Capital Lease Obligations
Maximum borrowing capacity				$ 250,000
Proceeds from issuance of debt			$ 250,000
Amount of term loan borrowings outstanding					$ 206,200
Effective interest rate (as a percent)					2.851%
Weighted average interest rate (as a percent)					2.523%
2014 Credit Facility \| Prime rate \| Revolving and Term Loan Borrowings \| Minimum
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					0.50%
2014 Credit Facility \| Prime rate \| Revolving and Term Loan Borrowings \| Maximum
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					1.00%
2014 Credit Facility \| Overnight Federal Funds rate \| Revolving and Term Loan Borrowings
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					0.50%
2014 Credit Facility \| Eurodollar rate for one month \| Revolving and Term Loan Borrowings
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					1.00%
2014 Credit Facility \| Eurodollar rate for selected interest period \| Revolving and Term Loan Borrowings \| Minimum
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					1.50%
2014 Credit Facility \| Eurodollar rate for selected interest period \| Revolving and Term Loan Borrowings \| Maximum
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					2.00%
2014 Credit Facility \| LIBOR \| Term Loan
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					1.625%
2016 Credit Facility
Long-term Debt and Capital Lease Obligations
Maximum borrowing capacity								$ 200,000
2016 Credit Facility \| Term Loan
Long-term Debt and Capital Lease Obligations
Maximum borrowing capacity								$ 200,000
Amount of term loan borrowings outstanding					$ 200,000
Effective interest rate (as a percent)					2.601%
Weighted average interest rate (as a percent)					2.276%
2016 Credit Facility \| Prime rate \| Term Loan \| Minimum
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					0.25%
2016 Credit Facility \| Prime rate \| Term Loan \| Maximum
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					0.75%
2016 Credit Facility \| Overnight Federal Funds rate \| Term Loan
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					0.50%
2016 Credit Facility \| Eurodollar rate for one month \| Term Loan
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					1.00%
2016 Credit Facility \| Eurodollar rate for selected interest period \| Term Loan \| Minimum
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					1.25%
2016 Credit Facility \| Eurodollar rate for selected interest period \| Term Loan \| Maximum
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)					1.75%
2016 Credit Facility \| LIBOR \| Term Loan
Long-term Debt and Capital Lease Obligations
Effective borrowing margin (as a percent)					1.375%
2017 Credit Facility
Long-term Debt and Capital Lease Obligations
Commitment commission (as a percent)		0.25%
2017 Credit Facility \| Term Loan
Long-term Debt and Capital Lease Obligations
Maximum borrowing capacity		$ 200,000
Proceeds from issuance of debt	$ 100,000	$ 100,000
Amount of term loan borrowings outstanding					$ 200,000
Effective interest rate (as a percent)					2.834%
Weighted average interest rate (as a percent)					2.57%
2017 Credit Facility \| Prime rate \| Term Loan
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)		0.625%
2017 Credit Facility \| Overnight Federal Funds rate \| Term Loan
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)		0.50%
2017 Credit Facility \| Eurodollar rate for one month \| Term Loan
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)		1.00%
2017 Credit Facility \| Eurodollar rate for selected interest period \| Term Loan
Long-term Debt and Capital Lease Obligations
Basis spread on variable rate (as a percent)		1.625%
2017 Credit Facility \| LIBOR \| Term Loan
Long-term Debt and Capital Lease Obligations
Effective borrowing margin (as a percent)					1.625%