Restructuring - Rollforward of Liability Balances (Detail) (Altona Plant [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period		$ 4,822
Expenses	2,500	2,974	9,000	10,800
Deductions		(4,868)
Balance at end of period		2,928		4,822
Employee Termination Benefit Charges [Member]
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period		1,408
Expenses		302
Deductions		(1,559)
Balance at end of period		151
Contract Termination Charges [Member]
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period		3,388
Expenses		1,409
Deductions		(2,269)
Balance at end of period		2,528
Other [Member]
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period		26
Expenses		1,263
Deductions		(1,040)
Balance at end of period		$ 249