Stock-Based Compensation (Employee Stock-Based Compensation Costs) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Stock-Based Compensation [Abstract]
Stock-based compensation costs - expensed	$ 2,921,000	$ 2,677,000	$ 8,883,000	$ 8,226,000
Stock-based compensation costs - capitalized	2,809,000	2,482,000	8,543,000	7,788,000
Unrecognized compensation cost related to unvested stock option and restricted stock grants	$ 38,200,000		$ 38,200,000
Weighted average period over which cost is recognized, years			2 years 3 months 18 days