Income Taxes (Details) $ / shares in Units, $ in Millions, ₩ in Billions	3 Months Ended
	Mar. 31, 2017 USD ($) $ / shares		Mar. 31, 2017 KRW (₩)	Mar. 31, 2016 USD ($) $ / shares
Income tax provision	$ 5.0	[1]		$ 3.1	[1]
Effective income tax rate (as a percent)	13.90%		13.90%	5.70%
Income tax benefit (expense) due to change in estimate related to uncertain tax position and adjustment for ASU 2016-09	$ (1.2)
Income tax benefit due to change in estimate related to uncertain tax position				$ 4.0
Special income tax concession period	5 years		5 years
Decrease in foreign income taxes due to special income tax concession	$ 0.8			$ 0.6
Impact of income tax concession on basic earnings per common share (in dollars per share) | $ / shares	$ 0.01			$ 0.01
Impact of income tax concession on diluted earnings per common share (in dollars per share) | $ / shares	$ 0.01			$ 0.01
Without income tax benefit adjustment
Effective income tax rate (as a percent)	10.60%		10.60%	15.40%
Tax Authority, South Korea (SRTO)
Pre-assessment notice, amount	$ 8.0		₩ 9.2

[1] Amounts may not add due to rounding