Share-Based Compensation and Employee Ownership Plans Stock Options (Details) $ / shares in Units, $ in Thousands			9 Months Ended	12 Months Ended
		Dec. 05, 2016	Sep. 30, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stockholders' Equity Note, Stock Split, Conversion Ratio		0.25
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate			0.00%
Aggregate Intrinsic Value
Closing stock price, in dollars per share			$ 17.80	$ 15.50
Equity Plans
Shares Subject to Option
Balance outstanding, beginning of period, shares | shares			4,167
Options granted, shares | shares			0
Stock Options exercised, shares | shares			0
Options expired, shares | shares			(4,167)
Balance outstanding, end of period, shares | shares			0	4,167
Options exercisable, shares | shares			0
Weighted Average Exercise Price/Share
Balance outstanding, beginning of period, in dollars per share			$ 19.56
Options granted, in dollars per share			0.00
Options exercised, in dollars per share			0.00
Options expired, in dollars per share			19.56
Balance outstanding, end of period, in dollars per share			0.00	$ 19.56
Options exercisable, in dollars per share			$ 0.00
Weighted average remaining term, options outstanding			0 years	1 month 6 days
Weighted average remaining term, options exercisable			0 years
Aggregate Intrinsic Value
Balance outstanding, beginning of period | $	[1]		$ 0
Balance outstanding, end of period | $	[1]		0	$ 0
Options exercisable | $	[1]		$ 0

[1] Based on the Company's closing stock price of $17.80 on September 30, 2017 and $15.50 on December 31, 2016.