Office Relocations (Narrative) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Gain (loss) on prior office leases	$ (9,902)
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Gain (loss) on prior office leases	(9,160)
Exploration and Production [Member]
Restructuring Cost and Reserve [Line Items]
Gain (loss) on prior office leases	$ (742)