Shareholders' Equity (Common And Equity Stock) (Details) (USD $)	0 Months Ended	3 Months Ended
	Nov. 07, 2013	Mar. 31, 2014	Mar. 31, 2013
Shareholders' Equity [Line Items]
Shares issued or sold	1,495,000
Proceeds from issuance of common stock	$ 192,300,000
Shares authorized for repurchase		6,500,000
Aggregate number of common stock repurchased in the period		0	0
Shares available for repurchase under existing repurchase program		1,600,000
Distributions paid to common shareholders		13,443,000	10,696,000
Common stock distributions per share		$ 0.50	$ 0.44
Equity stock, shares authorized		100,000,000
Since Inception [Member]
Shareholders' Equity [Line Items]
Aggregate number of common stock repurchased in the period		4,900,000
Aggregate cost of shares repurchased		$ 183,900,000
Average cost per share of common stock		$ 37.64
PS [Member]
Shareholders' Equity [Line Items]
Shares issued or sold	950,000