Property Transactions Property Transactions (Acquisition Pro Forma) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Document Fiscal Year Focus			2013
Revenues	$ 52,075	$ 39,286	$ 136,129	$ 105,160
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	55,888	1,110	112,842	5,037
Net income	65,037	13,278	122,763	12,154
Net Income (Loss) Available to Common Stockholders, Basic	59,381	9,444	106,975	2,733
Acquisition Pro Forma [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenues	80,698	80,426	243,927	228,581
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	58,756	5,153	123,702	17,167
Net income	67,905	17,321	133,623	24,284
Net Income (Loss) Available to Common Stockholders, Basic	$ 62,249	$ 13,487	$ 117,835	$ 14,863
Earnings Per Share, Basic	$ 0.33	$ 0.07	$ 0.62	$ 0.08
Earnings Per Share, Diluted	$ 0.33	$ 0.07	$ 0.62	$ 0.08