Equity Incentive Plans - Options by Exercise Price (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Granted, Wtd. Avg. grant date fair value (in dollars per share)	$ 3.96	$ 3.64	$ 5.91
Options granted (in shares)	391
Exercise prices and related information of stock option outstanding
Options outstanding, number outstanding (in shares)	1,590
Options outstanding, Wtd. Avg. remaining contractual life	6 years 10 months 24 days
Options outstanding, Wtd. Avg. exercise price (in dollars per share)	$ 24.29
Options exercisable, Number exercisable (in shares)	809
Options exercisable Wtd. Avg. Remaining Contractual Life	5 years 6 months 10 days
Options exercisable, Wtd. Avg. exercise price (in dollars per share)	$ 24.84
0-18.23
Exercise prices and related information of stock option outstanding
Lower range limit, Exercise price (in dollars per share)	0
Upper range limit, Exercise price (in dollars per share)	$ 18.23
Options outstanding, number outstanding (in shares)	112
Options outstanding, Wtd. Avg. remaining contractual life	1 year 8 months 23 days
Options outstanding, Wtd. Avg. exercise price (in dollars per share)	$ 14.54
Options exercisable, Number exercisable (in shares)	112
Options exercisable Wtd. Avg. Remaining Contractual Life	1 year 8 months 23 days
Options exercisable, Wtd. Avg. exercise price (in dollars per share)	$ 14.54
18.24-22.26
Exercise prices and related information of stock option outstanding
Lower range limit, Exercise price (in dollars per share)	18.24
Upper range limit, Exercise price (in dollars per share)	$ 22.26
Options outstanding, number outstanding (in shares)	618
Options outstanding, Wtd. Avg. remaining contractual life	7 years 1 month 28 days
Options outstanding, Wtd. Avg. exercise price (in dollars per share)	$ 21.00
Options exercisable, Number exercisable (in shares)	287
Options exercisable Wtd. Avg. Remaining Contractual Life	6 years 3 months
Options exercisable, Wtd. Avg. exercise price (in dollars per share)	$ 20.71
22.27-29.39
Exercise prices and related information of stock option outstanding
Lower range limit, Exercise price (in dollars per share)	22.27
Upper range limit, Exercise price (in dollars per share)	$ 29.39
Options outstanding, number outstanding (in shares)	519
Options outstanding, Wtd. Avg. remaining contractual life	7 years 7 months 9 days
Options outstanding, Wtd. Avg. exercise price (in dollars per share)	$ 25.07
Options exercisable, Number exercisable (in shares)	203
Options exercisable Wtd. Avg. Remaining Contractual Life	5 years 2 months 1 day
Options exercisable, Wtd. Avg. exercise price (in dollars per share)	$ 28.77
29.40-50.00
Exercise prices and related information of stock option outstanding
Lower range limit, Exercise price (in dollars per share)	29.4
Upper range limit, Exercise price (in dollars per share)	$ 50.00
Options outstanding, number outstanding (in shares)	341
Options outstanding, Wtd. Avg. remaining contractual life	7 years 14 days
Options outstanding, Wtd. Avg. exercise price (in dollars per share)	$ 32.31
Options exercisable, Number exercisable (in shares)	207
Options exercisable Wtd. Avg. Remaining Contractual Life	6 years 11 months 12 days
Options exercisable, Wtd. Avg. exercise price (in dollars per share)	$ 32.31