Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Jan. 17, 2017	Aug. 01, 2016	Dec. 31, 2016	Dec. 31, 2015	Jan. 12, 2015
Class Of Stock [Line Items]
Common stock, shares issued			85,316,000	85,049,000	5,750,000
Shares issued to underwriters					750,000
Public offering, realized net proceeds, net offering expenses					$ 41.9
At-the-market program, shares sold				0
Stock price as percentage of market value			100.00%
Remaining shares authorized under DRIP			2,841,000
OP units converted				40,000
Accrued preferred stock dividends			$ 1.6	$ 1.6
Dividends payable, date declared			Jan. 17, 2017
Dividends payable, date to be paid			Feb. 21, 2017
Dividends payable, date of record			Feb. 10, 2017
Subsequent Event [Member]
Class Of Stock [Line Items]
Common stock, dividends declared	$ 0.05
Forward Sales Agreement [Member]
Class Of Stock [Line Items]
Common stock, shares issued		5,750,000
Public offering, estimated net proceeds		$ 44.2
Series B [Member]
Class Of Stock [Line Items]
Dividend rate percentage			7.25%
Liquidation preference, per share			$ 25.00	$ 25.00
Redemption price per share			$ 25.00
At-the-market equity program, expiration date				May 29, 2015
Series B [Member] | Subsequent Event [Member]
Class Of Stock [Line Items]
Preferred stock dividends declared	$ 0.453125