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Pension And Profit Sharing Plans (Narrative) (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Defined contribution pension [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Contribution percentage of eligible employees compensation | 10.00% |  |
Vested after two years | 20.00% |  |
Vested after three years | 60.00% |  |
Vested after four years | 80.00% |  |
Vested after five years | 100.00% |  |
Pension expense | $ 2.0 | $ 1.0 | $ 3.0
Defined contribution pension [Member] | Maximum [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Maximum annual compensation subject to pension | $ 2.0 |  |
Qualified profit-sharing/401(k) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Contribution percentage of eligible employees compensation | 25.00% |  |
Vested after two years | 20.00% |  |
Vested after three years | 60.00% |  |
Vested after four years | 80.00% |  |
Vested after five years | 100.00% |  |
Pension expense | $ 1.0 | 1.0 | 2.0
Contributions percentage of employer match | 5.00% |  |
Non-qualified pension [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Pension expense | $ 2.0 | 2.0 | 1.0
Non-qualified profit-sharing/401(k) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Pension expense | $ 1.0 | $ 1.0 | $ 1.0

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- Definition Percentage of pension benefits vested due after five years. + References No definition available. + Details
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- Definition Percentage of pension benefits vested due after four years. + References No definition available. + Details
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- Definition Percentage of pension benefits vested due after three years. + References No definition available. + Details
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- Definition Percentage of pension benefits vested due after two years. + References No definition available. + Details
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- Definition The amount of pension benefit costs recognized during the period for (1) defined benefit plans and (2) defined contribution plans. For defined benefit plans, pension expense includes the following components: service cost, interest cost, expected return on plan assets, gain (loss) on plan assets, prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments. For defined contribution plans, the pension expense generally equals the firm's contribution to employees' accounts (if the firm contributes) during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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