Employee Benefit Plans (Narrative) (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Period of service before an employee is eligible for contribution	1 year
Common stock authorized for issuance but not yet issued for ESPP	247
Common stock authorized and reserved for ESPP	250
ESPP employee contribution, percentage	15.00%
Shares issued under ESPP	1	1	1
Fair value of investments in rabbi trust	$ 17,843	$ 18,331
Deferred Plan [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employer matching contribution, percentage on first 3%	100.00%
Employer matching contribution, percentage on next 2%	50.00%
Percentage of employees' gross pay for which the employer contributes a matching contribution of 100% under the Deferred Plan	3.00%
Percentage of employees' gross pay for which the employer contributes a matching contribution of 50% under the Deferred Plan	2.00%
Deferred compensation matching contributions	$ 225	617	$ 536
Total liabilities under Deferred Plan	$ 17,843	18,331
401(k) Plan [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employer matching contribution, percentage on first 3%	100.00%
Employer matching contribution, percentage on next 2%	50.00%
Percentage of employees' gross pay for which the employer contributes a matching contribution of 100%	3.00%
Percentage of employees' gross pay for which the employer contributes a matching contribution of 50%	2.00%
Period of service before an employee is eligible for contribution	1 year
Company matching contributions	$ 5,939	$ 4,995	$ 3,881

Common stock reserved for issuance under the Company's ESPP.

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Common stock authorized for issuance but not yet issued for ESPP

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Deferred Compensation Arrangement With Individual Employer Contribution Percentage On First 3 Percent

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Deferred Compensation Arrangement With Individual Employer Contribution Percentage On Next 2 Percent

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- Definition

Deferred compensation arrangement with individual, employer matching contribution of 100 percent

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Deferred compensation arrangement with individual, employer matching contribution of 50 percent

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Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay, at Which Employer Matches 100 Percent

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Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay, at Which Employer Matches 50 Percent

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Defined Contribution Plan, Employer Matching Contribution, Percent of Match On First 3%

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Defined Contribution Plan, Employer Matching Contribution, Percent of Match On Next 2 Percent

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- Definition

The maximum percent an employee may contribute after one year of service with the Company.

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Eligibility period to contribute to the ESPP.

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Eligibility period to receive matching contributions

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The amount of payment into the fund established for purposes of making future disbursements to the individual in accordance with the terms and understanding of the deferred compensation arrangement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements payable beyond one year (or the operating cycle, if longer).

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- Definition

The amount of the cost recognized during the period for defined contribution plans.

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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

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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