Variable Interest Entities Nonconsolidated VIEs (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2012
Variable Interest Entity [Line Items]
Investment in joint ventures	$ 24,482	$ 25,169	$ 24,207
Advances to joint ventures	99,053	55,696	111,878
Corporate Joint Venture [Member]
Variable Interest Entity [Line Items]
Investment in joint ventures	23,462	23,986	23,023
Advances to joint ventures			3,009
Joint venture, maximum loss exposure	$ 18,418	$ 19,363	$ 19,611