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Distributions - Summary of Distributions Paid Including Activity in Plan as well as Limited Partnership Units Issued from Reinvestment of Unit Distributions (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified
|
12 Months Ended |
|
Dec. 31, 2013
|
Dec. 31, 2012
|
Dec. 31, 2011
|
| Dividends [Line Items] |
|
|
|
| Preferred Stockholders |
$ 14,561 |
$ 15,140 |
$ 15,140 |
| Common Stockholders |
29,205 |
28,135 |
27,062 |
| Limited Partnership Unitholders |
9,956 |
9,956 |
8,339 |
| Dividend Reinvestments, Common Stock Issued (in shares) |
475,162 |
595,388 |
498,248 |
| Dividend Reinvestments, Limited Partnership Units Issued (in shares) |
88,309 |
|
|
|
October 31
|
|
|
|
| Dividends [Line Items] |
|
|
|
| Preferred Stockholders |
3,206 |
3,785 |
3,785 |
| Common Stockholders |
7,388 |
7,120 |
6,867 |
| Limited Partnership Unitholders |
2,489 |
2,489 |
2,489 |
| Dividend Reinvestments, Common Stock Issued (in shares) |
48,836 |
141,960 |
160,589 |
| Dividend Reinvestments, Discounted Share Price (in usd per share) |
$ 46.27 |
$ 42.23 |
$ 34.82 |
| Dividend Reinvestments, Limited Partnership Units Issued (in shares) |
88,309 |
|
|
| Dividend Reinvestments, Average Unit Price (in usd per share) |
$ 46.93 |
|
|
|
July 31
|
|
|
|
| Dividends [Line Items] |
|
|
|
| Preferred Stockholders |
3,206 |
3,785 |
3,785 |
| Common Stockholders |
7,327 |
7,063 |
6,772 |
| Limited Partnership Unitholders |
2,489 |
2,489 |
1,950 |
| Dividend Reinvestments, Common Stock Issued (in shares) |
138,019 |
144,881 |
125,973 |
| Dividend Reinvestments, Discounted Share Price (in usd per share) |
$ 45.21 |
$ 40.43 |
$ 38.30 |
|
April 30
|
|
|
|
| Dividends [Line Items] |
|
|
|
| Preferred Stockholders |
4,364 |
3,785 |
3,785 |
| Common Stockholders |
7,272 |
7,005 |
6,730 |
| Limited Partnership Unitholders |
2,489 |
2,489 |
1,950 |
| Dividend Reinvestments, Common Stock Issued (in shares) |
142,839 |
145,118 |
111,592 |
| Dividend Reinvestments, Discounted Share Price (in usd per share) |
$ 42.85 |
$ 38.93 |
$ 42.49 |
|
January 31
|
|
|
|
| Dividends [Line Items] |
|
|
|
| Preferred Stockholders |
3,785 |
3,785 |
3,785 |
| Common Stockholders |
7,218 |
6,947 |
6,693 |
| Limited Partnership Unitholders |
$ 2,489 |
$ 2,489 |
$ 1,950 |
| Dividend Reinvestments, Common Stock Issued (in shares) |
145,468 |
163,429 |
100,094 |
| Dividend Reinvestments, Discounted Share Price (in usd per share) |
$ 41.67 |
$ 34.44 |
$ 45.92 |