Summary of Share-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock option awards	$ 155	$ 387	$ (147)		$ 780
Other Stock Based Compensation Expense	(3,476)	729	(3,775)		1,326
Common, deferred, restricted and restricted unit awards	3,600
Share-based compensation			(3,922)	[1]	2,106
Allocated Share-based Compensation Expense	(3,333)	902	(3,941)		2,271
Defined Contribution Plan, Cost Recognized			300		500
Equity-classified awards:
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation	(3,321)	1,116	(3,922)		2,106
Liability-classified awards
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation	(12)	$ (214)	(19)		165
Accounts Payable and Accrued Liabilities | Performance Shares [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Deferred Compensation Share-based Arrangements, Liability, Current	$ 7,100		7,100
Other Pension Plan, Postretirement or Supplemental Plans [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Pension and Other Postretirement Benefit Expense			$ 100		$ 100

[1] Includes equity-classified share-based compensation of $(3,922) and $2,106 for the six months ended June 30, 2016 and 2015, respectively.