Stockholders' Equity 10K (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) item $ / shares shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) shares	May 30, 2016 USD ($)
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Authorized shares of common stock | shares	100,000,000	100,000,000
Voting rights per common share | item	1
Shares acquired by the entity | shares	46,000	40,000	56,000
Cost of shares acquired by the entity | $	$ 3.8	$ 2.5	$ 3.4
Number of business days after which rights distribution date occurs	10 days
Minimum percentage of beneficial ownership interest in the entity's common stock to be achieved by a person or group for the rights to be exercisable	15.00%
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Authorized shares of preferred stock | shares	20,000,000
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.01
Minimum number of series of preferred stock to be issued | item	1
Number of preferred shares issued | shares	0
2016 Stock Purchase Plan
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Authorized amount of repurchase under the stock purchase plan | $				$ 25.0
Preceding period in which repurchases were allowed under the plan	12 months
Common stock purchased under the stock purchase plan (in shares) | shares	91,542
Cost of shares of common stock acquired | $	$ 7.4
2015 Stock Purchase Plan
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Authorized amount of repurchase under the stock purchase plan | $	$ 25.0
Preceding period in which repurchases were allowed under the plan	12 months
Common stock purchased under the stock purchase plan (in shares) | shares	93,600	42,100	0
Cost of shares of common stock acquired | $	$ 5.2	$ 2.4	$ 0.0
2013 Stock Purchase Plan
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Authorized amount of repurchase under the stock purchase plan | $	$ 10.0
Preceding period in which repurchases were allowed under the plan	12 months
2014 Stock Purchase Plan
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common stock purchased under the stock purchase plan (in shares) | shares		60,900	22,600
Cost of shares of common stock acquired | $		$ 3.5	$ 1.2