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Compensation Plans: Stock Based (Details) $ / shares in Units, $ in Millions |  | 12 Months Ended
--- | --- | ---
Dec. 31, 2018 USD ($) $ / shares shares | Dec. 31, 2018 USD ($) shares $ / shares | Dec. 31, 2017 USD ($) $ / shares shares | Dec. 31, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Number of shares of common stock available for grant |  | 5,900,000 | 5,900,000 |  |
Impact outright issuance of one share has on number of available shares |  |  | 1 |  |
Director [Member] |  |  |  |  |
Director Shares |  |  |  |  |
Stock Issued During Period, Shares, Share-based Compensation, Gross |  |  | 63,741 | 71,573 | 53,473
Performance Shares [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Maximum impact of issuance of one performance share award on available shares under the equity incentive plan |  |  | 2 |  |
Multiplier applied to PSU awards at settlement |  | 0 | 0 | 0 | 0.2
Award vesting period |  | 3 years |  |  |
Stock-based compensation expense | $ |  |  | $ 10.3 | $ 9.7 | $ 11.0
Unrecognized stock based compensation expense | $ |  | $ 19.0 | $ 19.0 |  |
Multiplier assumed |  |  | 1 |  |
Fair value of PSUs/RSUs granted in period | $ |  |  | $ 14.0 | $ 15.5 | $ 11.9
Performance Share Units Shares Settled Gross of Shares for Tax Withholdings | [1] |  |  |  | 44,870
Shares held for settlement of income and payroll tax obligations (in shares) |  |  |  |  | (14,809)
Shares Issued in Period |  |  | 0 | 0 | 30,061
Fair value of PSUs/RSUs Vested in Period | $ |  |  | $ 10.3 | $ 8.1 | $ 8.4
Weighted Average Grant Date Fair Value |  |  |  |  |
Non-vested at beginning of year (in shares) | [2] |  | 1,533,491 | 828,923 | 626,328
Granted (in shares) | [2] |  | 572,924 | 977,731 | 447,971
Vested (in shares) | [2] |  | (233,102) | (94,338) | (130,353)
Forfeited (in shares) | [2] |  | (162,054) | (178,825) | (115,023)
Non-vested at end of year (in shares) | [2] | 1,711,259 | 1,711,259 | 1,533,491 | 828,923
Non-vested outstanding at the beginning of the period (in dollars per share) | $ / shares |  |  | $ 22.97 | $ 43.25 | $ 61.81
Granted (in dollars per share) | $ / shares |  |  | 24.45 | 15.86 | 26.56
Vested (in dollars per share) | $ / shares |  |  | 44.25 | 85.85 | 64.17
Forfeited (in dollars per share) | $ / shares |  |  | 21.79 | 44.99 | 55.59
Non-vested outstanding at the end of the period (in dollars per share) | $ / shares |  | $ 20.68 | $ 20.68 | $ 22.97 | $ 43.25
Director Shares |  |  |  |  |
Shares held for settlement of income and payroll tax obligations (in shares) |  |  |  |  | (14,809)
Performance Shares [Member] | Minimum [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Multiplier applied to PSU awards at settlement |  | 0 | 0 |  |
Performance Shares [Member] | Maximum [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Multiplier applied to PSU awards at settlement |  | 2 | 2 |  |
Restricted Stock Units (RSUs) [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Stock-based compensation expense | $ |  |  | $ 10.8 | $ 10.3 | $ 11.9
Unrecognized stock based compensation expense | $ |  | $ 20.0 | 20.0 |  |
Fair value of PSUs/RSUs granted in period | $ |  |  | $ 15.0 | $ 17.0 | $ 11.7
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vesting Increment |  |  | 0.33 | 0.33 | 0.33
Share-based compensation arrangement by share-based payment award, increment vesting period |  |  | 6 months |  |
Restricted Stock, Shares Settled Gross of Shares for Tax Withholdings | [3] |  | 407,529 | 246,025 | 241,363
Shares held for settlement of income and payroll tax obligations (in shares) |  |  | (115,784) | (74,747) | (72,181)
Shares Issued in Period |  |  | 291,745 | 171,278 | 169,182
Fair value of PSUs/RSUs Vested in Period | $ |  |  | $ 9.9 | $ 10.8 | $ 14.0
Number of Shares Represented by Each RSU |  |  | 1 |  |
Weighted Average Grant Date Fair Value |  |  |  |  |
Non-vested at beginning of year (in shares) |  |  | 1,244,262 | 604,116 | 543,737
Granted (in shares) |  |  | 583,552 | 1,020,780 | 417,065
Vested (in shares) |  |  | (407,529) | (246,025) | (241,363)
Forfeited (in shares) |  |  | (177,122) | (134,609) | (115,323)
Non-vested at end of year (in shares) |  | 1,243,163 | 1,243,163 | 1,244,262 | 604,116
Non-vested outstanding at the beginning of the period (in dollars per share) | $ / shares |  |  | $ 20.25 | $ 37.39 | $ 55.01
Granted (in dollars per share) | $ / shares |  |  | 25.77 | 16.64 | 28.08
Vested (in dollars per share) | $ / shares |  |  | 24.30 | 43.99 | 58.06
Forfeited (in dollars per share) | $ / shares |  |  | 17.26 | 26.38 | 43.52
Non-vested outstanding at the end of the period (in dollars per share) | $ / shares |  | $ 21.50 | $ 21.50 | $ 20.25 | $ 37.39
Director Shares |  |  |  |  |
Shares held for settlement of income and payroll tax obligations (in shares) |  |  | (115,784) | (74,747) | (72,181)
Restricted Stock Units (RSUs) [Member] | Director [Member] |  |  |  |  |
Weighted Average Grant Date Fair Value |  |  |  |  |
Granted (in shares) |  |  |  | 8,794 |
Shares Issued to the Board of Directors [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Stock-based compensation expense | $ |  |  | $ 1.7 | $ 1.6 | $ 2.0
[1] | (1) During the year ended December 31, 2016, the Company issued shares of common stock to settle PSUs that related to awards granted in 2013. The Company and a majority of grant recipients mutually agreed to net share settle a portion of the awards to cover income and payroll tax withholdings in accordance with the Company’s Equity Plan and individual award agreements.
[2] | (1) The number of awards assumes a multiplier of one. The final number of shares of common stock issued may vary depending on the three-year performance multiplier, which ranges from zero to two.
[3] | (1) During the years ended December 31, 2018, 2017, and 2016, the Company issued shares of common stock to settle RSUs that related to awards granted in previous years. The Company and a majority of grant recipients mutually agreed to net share settle a portion of the awards to cover income and payroll tax withholdings in accordance with the Company’s Equity Plan and individual award agreements.

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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + 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)(iv)(3) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event. + 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)(2)(iii)(3) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + 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)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + 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)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. + 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)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units. + 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)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period. + 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)(2)(iii)(2) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + 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 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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