Debt - Debt (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Debt	$ 434,413	$ 432,744
Senior Notes [Member]
Line of Credit Facility [Line Items]
Debt	250,000	250,000
Convertible Debt [Member]
Line of Credit Facility [Line Items]
Debt	104,020	103,194
Secured Debt [Member]
Line of Credit Facility [Line Items]
Debt	15,400	15,400
Other indebtedness [Member]
Line of Credit Facility [Line Items]
Debt	49,901	46,996
Six Percent Tangible Equity Units [Member]
Line of Credit Facility [Line Items]
Debt	$ 15,092	$ 17,154