Income Taxes - U.S. Federal Statutory Income Tax Rate Reconciled to Effective Rate (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Income tax expense at U.S. federal statutory rate	35.00%	35.00%	35.00%
Federal tax credits	(11.74%)	(4.13%)	(3.29%)
Taxing authority audit settlements and other tax adjustments	(3.47%)	(0.02%)	(0.47%)
Noncontrolling interests	(2.28%)	(1.16%)	(1.11%)
State and local income taxes, net of federal income tax benefit	9.81%	3.85%	3.46%
Tax rate differential on foreign income	2.11%	(0.96%)	(0.70%)
Tax impact of impairments	41.95%	0.57%
Other	2.37%	0.80%	0.72%
Provision for income taxes	73.75%	33.95%	33.61%