Common Stock and Other Equity Related Transactions - Common Stock, OP Units, and Distributions (Details) - $ / shares												12 Months Ended
	Oct. 14, 2016	Jul. 08, 2016	Apr. 08, 2016	Jan. 08, 2016	Oct. 09, 2015	Jul. 10, 2015	Apr. 10, 2015	Jan. 09, 2015	Oct. 10, 2014	Jul. 11, 2014	Apr. 11, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Equity [Abstract]
Units of partnership interest (in shares)												7,170,000	7,207,678	7,231,967
Common Stock Outstanding [Roll Forward]
Shares outstanding at January 1, (shares)												84,253,065	83,879,779	83,313,677
Common stock issued through the At-The-Market Offering Program (in shares)												683,548	0	0
Common stock issued through conversion of OP Units (in shares)												37,678	24,289	435,756
Common stock issued through exercise of options (in shares)												440,000	220,000	0
Common stock issued through stock grants (in shares)												133,726	158,013	186,666
Common stock issued through ESPP and Dividend Reinvestment Plan (in shares)												17,373	20,134	31,203
Common stock repurchased and retired (in shares)												(36,004)	(49,150)	(87,523)
Shares outstanding at December 31, (shares)												85,529,386	84,253,065	83,879,779
Share based payment award repurchased shares for taxes (usd per share)												$ 72.22	$ 66.20	$ 51.62
Percentage of ownership interests (in percentage)												92.30%	92.10%
Ownership percentage by noncontrolling owners (in percentage)												7.70%	7.90%
Disclosure Regular Quarterly Distributions Declared And Paid To Common Stockholders And Common O P Unit Non Controlling Interests [Abstract]
Distribution Amount Per Share (usd per share)	$ 0.425	$ 0.425	$ 0.425	$ 0.375	$ 0.375	$ 0.375	$ 0.375	$ 0.325	$ 0.325	$ 0.325	$ 0.325