Share and Unit-Based Plans: LTIP Activity (Details) (LTIP units, USD $)	0 Months Ended		12 Months Ended
	Jan. 31, 2013	Jan. 16, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
LTIP units
Units
Balance at beginning of year			0	200,000	190,000
Granted			725,908	332,189	315,000
Vested	(200,000)	(318,900)	(679,213)	(518,900)	(305,000)
Forfeited		(13,289)	0	(13,289)	0
Balance at end of year			46,695	0	200,000
Weighted Average Grant Date Fair Value (in dollars per share)
Balance at beginning of year			$ 0.00	$ 38.63	$ 43.30
Granted			$ 51.71	$ 66.58	$ 40.53
Vested			$ 51.22	$ 55.81	$ 44.85
Forfeited			$ 0.00	$ 66.58	$ 0.00
Balance at end of year			$ 58.89	$ 0.00	$ 38.63