Summary of Significant Accounting Policies (Stock-Based Compensation) (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended		3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	0 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	0 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Employee Stock Option	Sep. 30, 2014 Employee Stock Option	Sep. 30, 2014 Restricted stock awards	Sep. 30, 2014 Restricted stock awards	Apr. 25, 2014 Performance Shares	Sep. 30, 2014 Performance Shares	Sep. 30, 2014 Performance Shares	Sep. 30, 2014 PSUs	Sep. 30, 2014 PSUs	Sep. 30, 2014 SARs	Sep. 30, 2014 SARs	Apr. 25, 2014 End Of Measurement Period Vesting Performance Shares
Stock-based compensation
Total unrecognized compensation cost							$ 3,800,000	$ 3,800,000	$ 10,400,000	$ 10,400,000		$ 10,400,000	$ 10,400,000	$ 5,900,000	$ 5,900,000	$ 300,000	$ 300,000
Remaining weighted average vesting period for recognition of unrecognized compensation cost								1 year 1 month 6 days		2 years 6 months 4 days			2 years 6 months 25 days		1 year 10 months 28 days		1 year 5 months 8 days
Recognized compensation expense							1,500,000	4,300,000	1,100,000	2,600,000		1,100,000	1,800,000	500,000	1,600,000	38,000	59,000
Additional compensation expense related to dividend							$ 3,200,000	$ 9,700,000						$ 100,000	$ 600,000
Dividends paid per common share	$ 0.52	$ 0.52	$ 0.52	$ 0	$ 1.56	$ 0
Number of Award Shares
Outstanding at the beginning of the period (in shares)										419,067
E&P Purge (in shares)										106,261
Granted (in shares)										239,649
Released (in shares)										(237,618)
Canceled (in shares)										(59,018)
Outstanding at the end of the period (in shares)									468,341	468,341
Vesting period																		3 years
Period of total shareholder return upon which the percentage of shares vesting at the end of the measurement period will be based											3 years
Period of return of the MSCI US REIT index against which total shareholder return measured											3 years