Income Taxes (Income Tax Expense Reconciliation to Federal Rate) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Statutory federal income tax	$ 107,984	$ 92,325	$ 78,143
Less federal income tax assumed directly by noncontrolling interests	(65,142)	(55,715)	(48,394)
State income taxes, net of federal income tax benefit	5,539	5,309	3,642
Increase in valuation allowances	924	419	1,622
Interest related to unrecognized tax benefits	(155)	(109)	(83)
Other	604	135	43
Income tax expense	$ 49,754	$ 42,364	$ 34,973