Debt - Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Debt	$ 435,295	$ 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	105,672	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	53,324	46,996
Six Percent Tangible Equity Units [Member]
Line of Credit Facility [Line Items]
Debt	$ 10,899	$ 17,154