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Stock-based Compensation: Incentive Award Plan and Employee Stock Purchase Plan Stock-based Compensation: Incentive Award Plan and Employee Stock Purchase Plan (RSU and RSAs) (Details) - $ / shares | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 2,503,110 |  |
Award with service conditions [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] |  |  |
Unvested RSUs and RSAs outstanding at January 1 (in shares) | 465,369 |  |
Granted (in shares) | 134,897 |  |
Vested (in shares) | (310,000) |  |
Forfeited (in shares) | (11,004) |  |
Unvested RSUs and RSAs outstanding at December 31 (in shares) | 279,262 | 465,369 |
Unvested and expected to vest RSUs and RSAs outstanding at December 31 (in shares) | 259,412 |  |
Awards with performance and service conditions [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] |  |  |
Unvested RSUs and RSAs outstanding at January 1 (in shares) | 881,251 |  |
Granted (in shares) | 357,350 |  |
Vested (in shares) | (284,739) |  |
Forfeited (in shares) | (37,269) |  |
Unvested RSUs and RSAs outstanding at December 31 (in shares) | 916,593 | 881,251 |
Unvested and expected to vest RSUs and RSAs outstanding at December 31 (in shares) | 865,621 |  |
Restricted Stock Units and Awards [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] |  |  |
Unvested RSUs and RSAs outstanding at January 1 (in shares) | 1,346,620 |  |
Granted (in shares) | 492,247 |  |
Vested (in shares) | (594,739) |  |
Forfeited (in shares) | (48,273) |  |
Unvested RSUs and RSAs outstanding at December 31 (in shares) | 1,195,855 | 1,346,620 |
Unvested and expected to vest RSUs and RSAs outstanding at December 31 (in shares) | 1,125,033 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward] |  |  |
Unvested RSUs and RSAs outstanding at January 1, weighted average grant date fair value (in dollars per share) | $ 36.31 |  |
Granted, weighted average grant date fair value (in dollars per share) | 36.07 | $ 40.49 | $ 33.66
Vested, weighted average grant date fair value (in dollars per share) | $ 31.28 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures | 38.42 |  |
Unvested RSUs and RSAs outstanding at December 31, weighted average grant date fair value (in dollars per share) | $ 38.78 | $ 36.31 |
Unvested and expected to vest RSUs and RSAs outstanding at December 31, weighted average grant date fair value (in dollars per share) | $ 38.68 |  |

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- Definition Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested and Expected to Vest + References No definition available. + Details
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- Definition Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Unvested and Expected to Vest, Weighted Average Grant Date Fair Value + References No definition available. + Details
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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://www.xbrl.org/2003/role/presentationRef -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=6415400&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://www.xbrl.org/2003/role/presentationRef -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=6415400&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://www.xbrl.org/2003/role/presentationRef -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=6415400&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://www.xbrl.org/2003/role/presentationRef -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=6415400&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://www.xbrl.org/2003/role/presentationRef -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=6415400&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://www.xbrl.org/2003/role/presentationRef -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=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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=6415400&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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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