Debt (Details) In Millions, unless otherwise specified			1 Months Ended	3 Months Ended										1 Months Ended	3 Months Ended	1 Months Ended			1 Months Ended										1 Months Ended
	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	May 31, 2013 Senior notes 2021 Senior Notes (5.25% fixed rate) USD ($)	Mar. 31, 2015 Senior notes 2021 Senior Notes (5.25% fixed rate) USD ($)	Dec. 31, 2014 Senior notes 2021 Senior Notes (5.25% fixed rate) USD ($)	Mar. 31, 2015 Senior notes 2021 Senior Notes (5.25% fixed rate) Maximum USD ($)	Mar. 31, 2015 Line of credit Global Revolving Credit Facilities (variable rates) due December 2019 USD ($)	Dec. 31, 2014 Line of credit Global Revolving Credit Facilities (variable rates) due December 2019 USD ($)	Dec. 31, 2014 Line of credit U.S Revolving Credit Facility USD ($)	Dec. 31, 2014 Line of credit German Revolving Credit Facility USD ($)	Mar. 31, 2015 Secured debt Second German Loan Agreement (2.5% fixed rate) USD ($) installment	Mar. 31, 2015 Secured debt Second German Loan Agreement (2.5% fixed rate) EUR (€)	Dec. 31, 2014 Secured debt Second German Loan Agreement (2.5% fixed rate) USD ($) installment	Dec. 31, 2014 Secured debt Global Revolving Credit Facilities (variable rates) due December 2019 USD ($)	Mar. 31, 2015 Secured debt Global Revolving Credit Facilities (variable rates) due December 2019 USD ($)	Dec. 31, 2014 Secured debt Global Revolving Credit Facilities (variable rates) due December 2019 Minimum USD ($)	Dec. 31, 2014 Secured debt Global Revolving Credit Facilities (variable rates) due December 2019 Maximum USD ($)	Dec. 31, 2014 Secured debt U.S Revolving Credit Facility USD ($)	Dec. 31, 2014 Secured debt U.S Revolving Credit Facility Prime rate	Dec. 31, 2014 Secured debt U.S Revolving Credit Facility Federal funds rate	Dec. 31, 2014 Secured debt U.S Revolving Credit Facility LIBOR	Dec. 31, 2014 Secured debt U.S Revolving Credit Facility Minimum Prime rate	Dec. 31, 2014 Secured debt U.S Revolving Credit Facility Minimum Federal funds rate	Dec. 31, 2014 Secured debt U.S Revolving Credit Facility Minimum LIBOR	Dec. 31, 2014 Secured debt U.S Revolving Credit Facility Maximum Prime rate	Dec. 31, 2014 Secured debt U.S Revolving Credit Facility Maximum Federal funds rate	Dec. 31, 2014 Secured debt U.S Revolving Credit Facility Maximum LIBOR	Dec. 31, 2014 Secured debt German Revolving Credit Facility USD ($)	Dec. 31, 2014 Secured debt German Revolving Credit Facility LIBOR	Dec. 31, 2014 Secured debt German Revolving Credit Facility Minimum LIBOR	Dec. 31, 2014 Secured debt German Revolving Credit Facility Maximum LIBOR
Principal Payments
Total Debt	$ 223.2	$ 234.3		$ 175.0	$ 175.0		$ 39.1	$ 48.7			$ 9.1		$ 10.6
Less: Debt payable within one year	1.2	1.4
Long-term debt	222.0	232.9
Fixed rate of interest (as a percent)			5.25%	5.25%	5.25%						2.50%	2.50%
Number of equal quarterly installments											32	32	32
Total term of notes			8 years
Face amount			175
Maximum borrowing capacity that may be increased														50
Maximum borrowing capacity									20.0	2.0	9.1	8.4		250.0				125.0										75.0
Dividend restriction						25											25
Period to pay cash dividends on common stock				12 months										12 months
Available credit															155.2
Total outstanding															39.1
Borrowing availability to determine change of reporting obligations and controls																35	25
Borrowing availability for not achieving the fixed charge coverage ratio																	20
Percentage of aggregate commitments for not maintaining fixed charge coverage ratio																	10.00%
Percentage of aggregate commitments to determine the change of reporting obligations and controls																17.50%	12.50%
Percentage of aggregate commitments to determine the stock repurchases and dividend payments														12.50%
Period to be maintained for stock repurchase or dividend payment														60 days
Fixed charge coverage ratio required														1.1
Period for maintaining a fixed charge coverage ratio														12 months
Amount of the company's stock allowed to be repurchased in each fiscal year beginning in 2015														10
Borrowing availability to determine stock repurchases and dividend payments														$ 25
Debt instrument variable rate basis																			prime rate	federal funds	LIBOR								LIBOR
Debt instrument basis spread on variable rate (as a percent)																								2.50%			3.00%			1.50%	2.00%
Debt instrument reference rate																						0.00%	0.50%	0.00%	0.50%	1.00%				0.00%
Facility fee on unused amount of Revolver commitment (as a percent)															0.25%
Weighted-average interest rate (as a percent)															1.75%