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Stock-Based Compensation Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Stock-based Compensation Plans (Textual) [Abstract] |  |  |
Cash received from purchase plan purchases | $ 7,600 | $ 7,100 | $ 7,100
Stock-based compensation cost | 18,714 | 18,900 | 21,073
Unrecognized compensation cost related to stock-based compensation arrangements | $ 34,700 |  |
Weighted average period for recognition of cost | 3 years 2 months 12 days |  |
Incentive Plan |  |  |
Stock-based Compensation Plans (Textual) [Abstract] |  |  |
Shares available for issuance (in shares) | 842,532 |  |
Restricted Stock Awards |  |  |
Stock-based Compensation Plans (Textual) [Abstract] |  |  |
Fair value of shares vested during period | $ 15,200 | $ 19,200 | $ 16,500
Restricted Stock Awards | Maximum |  |  |
Stock-based Compensation Plans (Textual) [Abstract] |  |  |
Vesting period upon issuance (up to) | 5 years |  |
Employee Stock Purchase Plan |  |  |
Stock-based Compensation Plans (Textual) [Abstract] |  |  |
Shares available for issuance (in shares) | 991,087 |  |
Shares authorized for issuance (in shares) | 4,500,000 |  |
Employee stock purchase price in percentage of fair market value | 85.00% |  |
Shares issued to employees (in shares) | 148,007 | 123,448 | 152,138
Weighted average per share fair value of employee stock purchase rights issued (in dollars per share) | $ 15.15 | $ 16.51 | $ 13.40

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- Definition The total cash inflow associated with the amount received from employees to purchase company stock, including stock option exercises. + References No definition available. + Details
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- Definition Unrecognized cost of unvested share-based compensation awards. + 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 (i) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, 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 (i) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 + Details
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- Definition Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash. + 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 (d)(2) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + 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)(3) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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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=109197908&loc=d3e5070-113901 + Details
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