Financing Arrangements (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended
	Dec. 31, 2013 Senior Revolving Credit Facility Agreement	Dec. 31, 2011 Senior Revolving Credit Facility Agreement	Mar. 31, 2014 Unsecured bank lines of credit	Mar. 31, 2014 Credit lines related to corporate credit cards
Financing Arrangements
Maximum borrowing capacity		$ 250.0	$ 40.0	$ 6.9
Optional expansion, maximum borrowing capacity		150.0
Increased maximum borrowing capacity		400.0
Commitment fee as percentage of the variable margin		40.00%
Amortized loan fees written off	1.0
Outstanding bank guarantees under the letters of credit	$ 0		$ 7.1