Income Taxes - Narrative (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Taxes:
Income tax expense for income and the portion of earnings retained based on 162(m) limitations		$ 3.9
Years federal and state tax returns remain open for examination	2012, 2011 and 2010
Real Estate Investment Trust
Income Taxes:
REIT Taxable income distributed	100.00%
Income tax expense for income and the portion of earnings retained based on 162(m) limitations	$ 4.0	$ 1.9