Debt - Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Debt	$ 434,840	$ 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	104,846	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	51,586	46,996
Six Percent Tangible Equity Units [Member]
Line of Credit Facility [Line Items]
Debt	$ 13,008	$ 17,154