Segment Information (Revenue and Tangible Assets by Geographic Location) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Revenues from External Customers and Tangible Assets [Line Items]
Revenues	$ 721,858	$ 839,939	$ 498,729	$ 569,728	$ 785,708	$ 743,645	$ 706,968	$ 471,820	$ 2,630,254	$ 2,708,141	$ 1,587,579
Tangible Assets	2,782,651				2,671,452				2,782,651	2,671,452
Canada
Revenues from External Customers and Tangible Assets [Line Items]
Revenues									68,599	63,528	17,207
Tangible Assets	23,084				12,193				23,084	12,193
United States
Revenues from External Customers and Tangible Assets [Line Items]
Revenues									1,917,615	2,020,310	1,270,226
Tangible Assets	2,617,829				2,533,660				2,617,829	2,533,660
Other Foreign
Revenues from External Customers and Tangible Assets [Line Items]
Revenues									644,040	624,303	300,146
United Kingdom
Revenues from External Customers and Tangible Assets [Line Items]
Tangible Assets	139,433				122,624				139,433	122,624
Australia
Revenues from External Customers and Tangible Assets [Line Items]
Tangible Assets	$ 2,305				$ 2,975				$ 2,305	$ 2,975