Segment Information (Geographic Information) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from External Customers	$ 761,689	$ 804,879	$ 711,692	$ 693,438	$ 782,551	$ 784,051	$ 772,953	$ 745,095	$ 2,971,698	$ 3,084,650	$ 2,887,516
Long-Lived Assets	558,115				622,975				558,115	622,975
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from External Customers									1,248,217	1,247,166	1,072,139
Long-Lived Assets	235,665				287,802				235,665	287,802
France
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from External Customers									190,730	200,456	180,716
Long-Lived Assets	15,807				16,356				15,807	16,356
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from External Customers									382,521	434,051	363,296
Long-Lived Assets	62,203				67,245				62,203	67,245
Italy
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from External Customers									217,403	229,271	194,231
Long-Lived Assets	55,505				59,783				55,505	59,783
Spain
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from External Customers									238,235	252,801	231,304
Long-Lived Assets	86,267				89,234				86,267	89,234
Poland
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from External Customers									105,813	107,519	112,972
Long-Lived Assets	48,734				35,406				48,734	35,406
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from External Customers									588,779	613,386	732,858
Long-Lived Assets	$ 53,934				$ 67,149				$ 53,934	$ 67,149