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Shareholders' Equity and Share-Based Compensation - Narrative (Details) | 12 Months Ended |
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Dec. 31, 2020 USD ($) $ / shares shares | Dec. 31, 2019 USD ($) $ / shares shares | Dec. 31, 2018 $ / shares shares | Dec. 31, 2017 USD ($) $ / shares | Dec. 31, 2015 shares | Dec. 31, 2012 | Sep. 30, 2015 USD ($) $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Common stock, par value (in usd per share) | $ 0.001 | $ 0.001 | $ 0.001 |  |  |  |
Shares reacquired during period (in shares) | shares | 899,468 | 52,095 | 129,112 |  |  |  |
Percentage of outstanding shares reacquired |  | 0.10% | 0.30% |  |  |  |
Shares reacquired during period, value | $ |  | $ 2,200,000 |  | $ 5,100,000 |  |  |
Share price of treasury stock acquired during period (in usd per share) | $ 32.68 | $ 41.17 |  | $ 39.41 |  |  |
Remaining authorized repurchase amount | $ | $ 20,600,000 |  |  |  |  |  |
Treasury stock (in shares) | shares | 24,902,579 | 24,850,484 |  |  |  |  |
Preferred stock, shares authorized (in shares) | shares | 1,000,000 | 1,000,000 |  |  |  |  |
Preferred stock, par value (in usd per share) | $ 0.001 | $ 0.001 |  |  |  |  |
Fungible share pool, grant of full value share conversion ratio |  |  |  |  |  | 2.5 |
Intrinsic value | 0 |  |  |  |  |  |
Weighted average exercise prices of vested and exercisable options (in usd per share) | 36.59 | $ 34.81 | $ 31.42 |  |  |  |
Share price (in usd per share) | $ 42.04 |  |  |  |  |  |
Aggregate intrinsic value of vested options | $ | $ 2,500,000 |  |  |  |  |  |
Aggregate intrinsic value of options | $ | $ 2,900,000 |  |  |  |  |  |
Minimum |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Expiration period | 7 years |  |  |  |  |  |
Minimum | Employee stock option |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Vesting period | 4 years |  |  |  |  |  |
Minimum | Restricted stock units |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Vesting period | 1 year |  |  |  |  |  |
Maximum |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Expiration period | 10 years |  |  |  |  |  |
Maximum | Restricted stock units |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Vesting period | 5 years |  |  |  |  |  |
2015 Plan |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Authorized repurchase amount | $ |  |  |  |  |  |  | $ 50,000,000.0
Common stock, par value (in usd per share) |  |  |  |  |  |  | $ 0.001
Comprehensive Plan |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Amended increase in shares reserved for issuance (in shares) | shares |  |  |  |  | 3,250,000 |  |
Shares available for grant (in shares) | shares | 751,661 |  |  |  |  |  |

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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + 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 -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Period from grant date that an equity-based award expires, 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 (a)(2) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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