Description of Business and Summary of Significant Accounting Policies - Additional Information (Details)
$ in Thousands |
3 Months Ended |
12 Months Ended |
|
Dec. 31, 2017
USD ($)
|
Sep. 29, 2017
USD ($)
|
Jun. 30, 2017
USD ($)
|
Mar. 31, 2017
USD ($)
|
Dec. 31, 2016
USD ($)
|
Sep. 30, 2016
USD ($)
|
Jul. 01, 2016
USD ($)
|
Apr. 01, 2016
USD ($)
|
Dec. 31, 2017
USD ($)
segment
|
Dec. 31, 2016
USD ($)
|
Dec. 31, 2015
USD ($)
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| Accounting Policies [Line Items] |
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| Number of reportable segments | segment |
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1
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| Revenue |
$ 295,782
|
$ 269,625
|
$ 259,318
|
$ 290,063
|
$ 288,160
|
$ 283,782
|
$ 307,895
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$ 310,682
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$ 1,114,788
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$ 1,190,519
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$ 1,180,684
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| Goodwill impairment charges |
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0
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0
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0
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| Goodwill, acquired |
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$ 0
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0
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0
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| Buildings and improvements | Minimum |
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| Accounting Policies [Line Items] |
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| Estimated useful life |
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5 years
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| Buildings and improvements | Maximum |
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| Accounting Policies [Line Items] |
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| Estimated useful life |
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40 years
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| Machinery and equipment | Minimum |
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| Accounting Policies [Line Items] |
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| Estimated useful life |
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3 years
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| Machinery and equipment | Maximum |
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| Accounting Policies [Line Items] |
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| Estimated useful life |
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10 years
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| Furniture, fixtures, and office equipment | Minimum |
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| Accounting Policies [Line Items] |
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| Estimated useful life |
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3 years
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| Furniture, fixtures, and office equipment | Maximum |
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| Accounting Policies [Line Items] |
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| Estimated useful life |
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7 years
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| Government customers |
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| Accounting Policies [Line Items] |
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| Revenue |
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$ 1,100,000
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$ 1,200,000
|
$ 1,200,000
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| Total revenue | Credit risk | U.S. Army |
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| Accounting Policies [Line Items] |
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| Concentration risk, percentage |
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82.00%
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84.00%
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85.00%
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| High Desert Support Services (HDSS) |
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| Accounting Policies [Line Items] |
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| Ownership percentage |
40.00%
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40.00%
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