Income Tax (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, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Current
Federal taxes									$ 8,673	$ 30,382	$ 36,109
State taxes									2,380	5,019	8,614
Foreign taxes									252	190	73
Total current taxes									11,305	35,591	44,796
Deferred
Federal taxes									(2,894)	(8,469)	(3,571)
State taxes									(897)	(742)	(502)
Foreign taxes									(193)	(190)	(73)
Total deferred taxes									(3,984)	(9,401)	(4,146)
Provision for income taxes	$ 2,077	$ (6,606)	$ 5,465	$ 6,385	$ 1,898	$ 7,649	$ 8,811	$ 7,832	$ 7,321	$ 26,190	$ 40,650