Stock Plans - Option Exercise Ranges and FV Assumptions (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Options Outstanding
Options Outstanding, Shares	1,576,000
Weighted Average Remaining Contractual Life	4 years 10 months 24 days
Weighted-Average Exercise Price (in dollars per share)	$ 35.18
Options Exercisable
Options Exercisable, Shares	1,449,000
Aggregate Intrinsic Value	$ 39
Weighted Average Remaining Contractual life	4 years 10 months 24 days
Weighted Average Exercise Price (in dollars per share)	$ 35.39
$20.00 - $30.00
Information about stock options outstanding
Exercise price, low end of range (in dollars per share)	20.00
Exercise price, high end of range (in dollars per share)	$ 30.00
Options Outstanding
Options Outstanding, Shares	32,000
Weighted Average Remaining Contractual Life	5 years 9 months 18 days
Weighted-Average Exercise Price (in dollars per share)	$ 28.18
Options Exercisable
Options Exercisable, Shares	29,000
Aggregate Intrinsic Value	$ 39
Weighted Average Remaining Contractual life	5 years 10 months 24 days
Weighted Average Exercise Price (in dollars per share)	$ 28.04
$30.01 - $40.00
Information about stock options outstanding
Exercise price, low end of range (in dollars per share)	30.01
Exercise price, high end of range (in dollars per share)	$ 40.00
Options Outstanding
Options Outstanding, Shares	1,336,000
Weighted Average Remaining Contractual Life	5 years 1 month 6 days
Weighted-Average Exercise Price (in dollars per share)	$ 33.09
Options Exercisable
Options Exercisable, Shares	1,212,000
Weighted Average Remaining Contractual life	5 years 1 month 6 days
Weighted Average Exercise Price (in dollars per share)	$ 33.12
$40.01 - $50.00
Information about stock options outstanding
Exercise price, low end of range (in dollars per share)	40.01
Exercise price, high end of range (in dollars per share)	$ 50.00
Options Outstanding
Options Outstanding, Shares	73,000
Weighted Average Remaining Contractual Life	2 years 8 months 12 days
Weighted-Average Exercise Price (in dollars per share)	$ 45.93
Options Exercisable
Options Exercisable, Shares	73,000
Weighted Average Remaining Contractual life	2 years 8 months 12 days
Weighted Average Exercise Price (in dollars per share)	$ 45.96
$50.01 - $60.00
Information about stock options outstanding
Exercise price, low end of range (in dollars per share)	50.01
Exercise price, high end of range (in dollars per share)	$ 60.00
Options Outstanding
Options Outstanding, Shares	135,000
Weighted Average Remaining Contractual Life	4 years 4 months 24 days
Weighted-Average Exercise Price (in dollars per share)	$ 51.70
Options Exercisable
Options Exercisable, Shares	135,000
Weighted Average Remaining Contractual life	4 years 4 months 24 days
Weighted Average Exercise Price (in dollars per share)	$ 51.70
2016 Employee Stock Purchase Plan
Assumptions based on which fair value of each option granted was estimated using the Black-Scholes option-pricing model
Proceeds from issue of shares under ESPP Plan	$ 1,200
Number of shares issued under ESPP Plan	83,000
Weighted average fair value (in dollars per share)	$ 4.45
Dividend yield (as a percent)	0.00%
Expected volatility factor (as a percent)	43.00%
Risk-free interest rate (as a percent)	0.35%
Expected life (in years)	6 months
Stock option Awards
Options Exercisable
Granted (in shares)	0	17,000	509,000
Assumptions based on which fair value of each option granted was estimated using the Black-Scholes option-pricing model
Weighted average fair value (in dollars per share)		$ 10.58	$ 11.58
Dividend yield (as a percent)		0.00%	0.00%
Expected volatility factor (as a percent)		44.00%	44.00%
Risk-free interest rate (as a percent)		1.18%	1.19%
Expected life (in years)		3 years 10 months 24 days	3 years 10 months 24 days