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Benefit Plans - Options Outstanding and Options Exercisable by Exercise Price with Weighted-Average Remaining Contractual Life for Options Outstanding and Weighted-Average Exercise Price (Detail) | 12 Months Ended
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Dec. 31, 2018 $ / shares shares
Exercise Price 20-25 [Member] |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
Exercise Price Lower Range Limit | $ 20
Exercise Price Upper Range Limit | $ 25
Options Outstanding, Number | shares | 349,990
Options Outstanding, Weighted-Average Remaining Contractual Life (Years) | 4 years 2 months 1 day
Options Outstanding, Weighted-Average Grant Date Value | $ 24.60
Options Exercisable, Number | shares | 109,150
Options Exercisable, Weighted-Average Grant Date Value | $ 24.60
Exercise Price 25-30 [Member] |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
Exercise Price Lower Range Limit | 25
Exercise Price Upper Range Limit | $ 30
Options Outstanding, Number | shares | 33,970
Options Outstanding, Weighted-Average Remaining Contractual Life (Years) | 2 years 2 months 8 days
Options Outstanding, Weighted-Average Grant Date Value | $ 27.99
Options Exercisable, Number | shares | 24,460
Options Exercisable, Weighted-Average Grant Date Value | $ 29.10
Exercise Price 30-35 [Member] |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
Exercise Price Lower Range Limit | 30
Exercise Price Upper Range Limit | $ 35
Options Outstanding, Number | shares | 448,300
Options Outstanding, Weighted-Average Remaining Contractual Life (Years) | 4 years 3 months 25 days
Options Outstanding, Weighted-Average Grant Date Value | $ 33.31
Options Exercisable, Number | shares | 165,675
Options Exercisable, Weighted-Average Grant Date Value | $ 33.03
Exercise Price 35-40 [Member] |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
Exercise Price Lower Range Limit | 35
Exercise Price Upper Range Limit | $ 40
Options Outstanding, Number | shares | 7,900
Options Outstanding, Weighted-Average Remaining Contractual Life (Years) | 4 years 6 months 29 days
Options Outstanding, Weighted-Average Grant Date Value | $ 38.83
Options Exercisable, Number | shares | 3,600
Options Exercisable, Weighted-Average Grant Date Value | $ 38.56
Exercise Price 40-45 [Member] |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
Exercise Price Lower Range Limit | 40
Exercise Price Upper Range Limit | $ 45
Options Outstanding, Number | shares | 5,440
Options Outstanding, Weighted-Average Remaining Contractual Life (Years) | 5 years 8 months 1 day
Options Outstanding, Weighted-Average Grant Date Value | $ 40.37
Options Exercisable, Number | shares | 340
Options Exercisable, Weighted-Average Grant Date Value | $ 40.37
Exercise Price 20-45 [Member] |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
Exercise Price Lower Range Limit | 20
Exercise Price Upper Range Limit | $ 45
Options Outstanding, Number | shares | 845,600
Options Outstanding, Weighted-Average Remaining Contractual Life (Years) | 4 years 2 months 4 days
Options Outstanding, Weighted-Average Grant Date Value | $ 29.57
Options Exercisable, Number | shares | 303,225
Options Exercisable, Weighted-Average Grant Date Value | $ 29.71

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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. + Details
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- Definition The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(iii) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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