Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Health Insurance
Health insurance maximum risk of loss liability per employee insurance plan (up to)			$ 350,000
Health insurance maximum aggregate amount of risk of loss liability for employee insurance plans (up to)			$ 700,000
Earnings per Share
Common stock equivalents (in shares)	209	155	294	151
Anti-dilutive common stock equivalents (in shares)	0	0	0	0
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Selling, general and administrative expenses	$ 82,506,000	$ 85,474,000	$ 167,184,000	$ 170,929,000
Other expense, net	1,357,000	831,000	2,542,000	1,499,000
Cash provided by operating activities			5,539,000	15,951,000
Deferred tax assets, net, noncurrent	21,081,000		$ 21,081,000		$ 23,449,000
Percent of timing of revenue recognition not impacted by new accounting pronouncement			95.00%
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption					(469,000)
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Excess tax benefits from share-based compensation	0		$ 200,000
Decrease in effective income tax rate			0.90%
Increase to earnings per share (in dollars per share)			$ 0.01
Cash provided by operating activities			$ 200,000	300,000
Deferred tax assets, net	300,000		300,000		300,000
Accounting Standards Update 2016-09 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption					500,000
Accounting Standards Update 2015-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred tax assets, net, current					(4,800,000)
Deferred tax assets, net, noncurrent					$ 4,800,000
New Accounting Pronouncement, Early Adoption, Effect | Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Selling, general and administrative expenses	(100,000)	(100,000)	(300,000)	(200,000)
Other expense, net	$ 100,000	$ 100,000	$ 300,000	$ 200,000