Segment Reporting - Information about Operations in Different Segments (Parenthetical) (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Capital expenditures	$ 23,972,000	$ 37,893,000
Accrued Capital Expenditures of 2014 [Member]
Segment Reporting Information [Line Items]
Capital expenditures	3,300,000
Accrued Capital Expenditures of 2013 [Member]
Segment Reporting Information [Line Items]
Capital expenditures		8,300,000
ASA [Member]
Segment Reporting Information [Line Items]
Impairment charge	4,200,000
Capital expenditures	$ 10,824,000	$ 4,068,000