Debt instrument principle including make-whole premium.

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- Definition

Debt instrument redemption price percentage on change of control.

+ References

No definition available.

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- Definition

Debt instrument redemption price percentage on change of control, description.

+ References

No definition available.

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- Definition

Amount of amortization expense attributable to debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
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-Topic 220
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28555-108399

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- Definition

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

+ References

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-Publisher FASB
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- Definition

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

+ References

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- Definition

Date the debt instrument was issued, in CCYY-MM-DD format.

+ References

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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.

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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- Definition

Description of the payment terms of the debt instrument (for example, whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment.

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-Publisher FASB
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- Definition

Description of debt redemption features under terms of the debt agreement.

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-SubTopic 470
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- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

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- Definition

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

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- Definition

The cash inflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

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- Definition

The cash outflow for the settlement of obligation drawn from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

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Long Term Debt - Senior Notes - Additional Information (Detail) - USD ($) $ in Millions							3 Months Ended		6 Months Ended
	Dec. 16, 2019	Nov. 15, 2019	Sep. 25, 2019	Jan. 19, 2018	Jun. 14, 2012	Oct. 05, 2010	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Debt Instrument [Line Items]
Interest expense related to amortization of debt issuance costs							$ 0.2	$ 0.3	$ 0.5	$ 0.7
Revolving Credit Facility
Debt Instrument [Line Items]
Repayment of borrowings				$ 239.0
4.97% Series A Senior Notes, Due October 5th 2020
Debt Instrument [Line Items]
Debt maturity date						Oct. 05, 2020
Long-term debt, aggregate principal amount						$ 300.0
Debt interest rate						4.97%
Notes issuance date						Oct. 05, 2010
Debt Instrument principle including make-whole premium			$ 308.0
Debt instrument, redemption percentage			100.00%
4.27% Series B Senior Notes, Due June 14th 2022
Debt Instrument [Line Items]
Debt maturity date					Jun. 14, 2022
Long-term debt, aggregate principal amount					$ 300.0
Debt interest rate					4.27%
Notes issuance date					Jun. 14, 2012
Debt Instrument principle including make-whole premium	$ 315.0
Debt instrument, redemption percentage	100.00%
3.95% Senior Notes Due 2028
Debt Instrument [Line Items]
Debt maturity date				Feb. 01, 2028
Long-term debt, aggregate principal amount				$ 525.0
Debt interest rate				3.95%			3.95%		3.95%		3.95%
Debt instrument, redemption percentage				100.00%
Proceeds from borrowings, before offering expenses				$ 521.0
Debt payment term									We pay interest on the 2028 Notes on February 1 and August 1 of each year.
Debt instrument redemption description									We, at our option, may redeem the Senior Notes in whole or in part, at any time or from time to time at a redemption price equal to 100% of the principal amount of such Senior Notes to be redeemed, plus accrued and unpaid interest, if any, on those Senior Notes to the redemption date, plus a “make-whole” premium. Additionally, commencing on November 1, 2027, in the case of the 2028 Notes, and on August 15, 2029, in the case of the 2029 Notes, we, at our option, may redeem the respective Senior Notes in whole or in part, at a redemption price equal to 100% of the principal amount of the Senior Notes to be redeemed, plus accrued and unpaid interest, if any, on those Senior Notes to the redemption date.
Debt instrument redemption upon the occurrence of change of control, description									Upon the occurrence of a change of control triggering event, as defined in the indentures, each holder of the Senior Notes may require us to purchase all or a portion of such holder’s Senior Notes at a price equal to 101% of their principal amount, plus accrued and unpaid interest, if any, to, but excluding, the repurchase date.
Redemption price percentage of principal amount of debt instrument on change of control				101.00%
5.15% Senior Notes Due 2029
Debt Instrument [Line Items]
Debt maturity date		Nov. 15, 2029
Long-term debt, aggregate principal amount		$ 350.0
Debt interest rate		5.15%					5.15%		5.15%		5.15%
Debt instrument, redemption percentage		100.00%
Proceeds from borrowings, before offering expenses		$ 347.0
Debt payment term									We pay interest on the 2029 Notes on May 15 and November 15 of each year.
Debt instrument redemption description									We, at our option, may redeem the Senior Notes in whole or in part, at any time or from time to time at a redemption price equal to 100% of the principal amount of such Senior Notes to be redeemed, plus accrued and unpaid interest, if any, on those Senior Notes to the redemption date, plus a “make-whole” premium. Additionally, commencing on November 1, 2027, in the case of the 2028 Notes, and on August 15, 2029, in the case of the 2029 Notes, we, at our option, may redeem the respective Senior Notes in whole or in part, at a redemption price equal to 100% of the principal amount of the Senior Notes to be redeemed, plus accrued and unpaid interest, if any, on those Senior Notes to the redemption date.
Term Loan Agreement
Debt Instrument [Line Items]
Repayment of borrowings	$ 50.0
Debt issuance costs							$ 0.4		$ 0.4