Deferred Charges and Other Assets, net: (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Deferred Charges and Other Assets, net:
Leasing	$ 234,498	$ 281,340
Financing	42,868	40,638
Intangible assets:
In-place lease values	175,735	121,320
Leasing commissions and legal costs	46,419	32,242
Above-market leases	118,033	97,297
Deferred tax assets	33,414	26,829
Deferred compensation plan assets	24,670	20,646
Acquisition deposit	30,000
Other assets	72,811	53,824
Deferred charges and other assets, gross	778,448	674,136
Less accumulated amortization	(213,318)	(190,373)
Deferred charges and other assets, net	565,130	483,763
Accumulated amortization for in-place lease values, leasing commissions and legal costs	62,792	56,946
Amortization expense for intangible assets	$ 33,517	$ 15,492	$ 14,886