Note 2 - Basis of Presentation (Detail) - Reconciliation of Carrying Amounts for Equity and Related Amounts or Equity Attributable to Stockholders' Equity and Noncontrolling Interests (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended			6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Common Stock [Member]	Dec. 31, 2011 Common Stock [Member]	Jun. 30, 2012 Additional Paid-in Capital [Member]	Jun. 30, 2012 Retained Earnings [Member]	Jun. 30, 2012 Noncontrolling Interest [Member]
Balance, December 31, 2011			$ 553,087		$ 23	$ 23	$ 175,900	$ (32,962)	$ 410,126
Net income	13,709	7,370	26,962	17,305				5,624	21,338
Amortization of previously granted share awards	1	14	2	29			2
Conversions of operating partnership units			821				821		(821)
Dividends and distributions			(37,747)					(7,933)	(29,814)
Balance, June 30, 2012	$ 542,304		$ 542,304		$ 23	$ 23	$ 176,723	$ (35,271)	$ 400,829

Note 2 - Basis of Presentation (Detail) - Reconciliation of Carrying Amounts for Equity and Related Amounts or Equity Attributable to Stockholders' Equity and Noncontrolling Interests (USD $)
In Thousands, unless otherwise specified

3 Months Ended

6 Months Ended

Jun. 30, 2012

Jun. 30, 2011

Jun. 30, 2012

Jun. 30, 2011

Jun. 30, 2012

Common Stock [Member]

Dec. 31, 2011

Common Stock [Member]

Jun. 30, 2012

Additional Paid-in Capital [Member]

Jun. 30, 2012

Retained Earnings [Member]

Jun. 30, 2012

Noncontrolling Interest [Member]

Balance, December 31, 2011

$ 553,087

$ 23

$ 175,900

$ (32,962)

$ 410,126

Net income

13,709

7,370

26,962

17,305

5,624

21,338

Amortization of previously granted share awards

Conversions of operating partnership units

821

(821)

Dividends and distributions

(37,747)

(7,933)

(29,814)

Balance, June 30, 2012

$ 542,304

$ 23

$ 176,723

$ (35,271)

$ 400,829

- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References+ Details

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph A1, A4, A5

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 19

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4569616-111683

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 29

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 5

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 55

-Paragraph 4K

-URI http://asc.fasb.org/extlink&oid=18733213&loc=SL4591552-111686

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=18733093&loc=SL4573702-111684

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 38

-Subparagraph c(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 38

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 55

-Paragraph 4J

-URI http://asc.fasb.org/extlink&oid=18733213&loc=SL4591551-111686

+ Details

- Definition

Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

+ References+ Details