Derivative Instruments and Hedging Activities	12 Months Ended
Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities The Company uses interest rate swaps, interest rate caps, and total return swap contracts to manage certain interest rate risks. The valuation of these instruments is determined using widely accepted valuation techniques including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves. The fair values of interest rate swaps and total return swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves. The Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In November 2016, the Company replaced its $225.0 million term loan with a $350.0 million five-year term loan with a delayed draw feature. The term loan carries a variable interest rate of LIBOR plus 95 basis points. In 2016, the Company entered into four forward starting interest rate swaps (settlement payments commenced in March 2017) and in 2017, the Company entered into one forward starting interest rate swap (settlement payments commenced in March 2017) all related to the $350.0 million term loan. These five swaps, with a total notional amount of $175.0 million bear an average fixed interest rate of 2.3% and are scheduled to mature in February 2022. These derivatives qualify for hedge accounting. As of December 31, 2017 and 2016, the Company had interest rate caps, which were not accounted for as hedges, with an aggregate notional amount of $20.7 million, which effectively limits the Company’s exposure to interest rate risk by providing a ceiling on the underlying variable interest rate for a portion of the Company’s tax exempt variable rate debt. As of December 31, 2017 and 2016, the aggregate carrying value of the interest rate swap contracts was an asset of $5.4 million and $4.4 million, respectively, and is included in prepaid expenses and other assets on the consolidated balance sheets, and a liability of zero and $0.03 million, respectively, and is included in other liabilities on the consolidated balance sheets. The aggregate carrying value of the interest rate cap was zero on the balance sheet as of December 31, 2017 and December 31, 2016. Hedge ineffectiveness related to cash flow hedges, which is reported in current year income as interest expense was $0.1 million and $0.3 million of income for the years ended December 31, 2017 and 2016, respectively. Hedge ineffectiveness was not significant for the year ended December 31, 2015. Additionally, the Company has entered into total return swaps that effectively convert $256.6 million of mortgage notes payable to a floating interest rate based on SIFMA plus a spread. The total return swaps provide fair market value protection on the mortgage notes payable to its counterparties during the initial period of the total return swap until the Company's option to call the mortgage notes at par can be exercised. The Company can currently call all of the total return swaps with $256.6 million of the outstanding debt at par. These derivatives do not qualify for hedge accounting and had a carrying and fair value of zero at both December 31, 2017 and 2016. These total return swaps are scheduled to mature between September 2021 and November 2022. The realized gains of $10.1 million, $11.7 million, and $5.7 million as of December 31, 2017, 2016, and 2015, respectively, were reported in current year income as total return swap income.

Derivative Instruments and Hedging Activities

The Company uses interest rate swaps, interest rate caps, and total return swap contracts to manage certain interest rate risks. The valuation of these instruments is determined using widely accepted valuation techniques including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves. The fair values of interest rate swaps and total return swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves. The Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements.

In November 2016, the Company replaced its $225.0 million term loan with a $350.0 million five-year term loan with a delayed draw feature. The term loan carries a variable interest rate of LIBOR plus 95 basis points. In 2016, the Company entered into four forward starting interest rate swaps (settlement payments commenced in March 2017) and in 2017, the Company entered into one forward starting interest rate swap (settlement payments commenced in March 2017) all related to the $350.0 million term loan. These five swaps, with a total notional amount of $175.0 million bear an average fixed interest rate of 2.3% and are scheduled to mature in February 2022. These derivatives qualify for hedge accounting.

As of December 31, 2017 and 2016, the Company had interest rate caps, which were not accounted for as hedges, with an aggregate notional amount of $20.7 million, which effectively limits the Company’s exposure to interest rate risk by providing a ceiling on the underlying variable interest rate for a portion of the Company’s tax exempt variable rate debt.

As of December 31, 2017 and 2016, the aggregate carrying value of the interest rate swap contracts was an asset of $5.4 million and $4.4 million, respectively, and is included in prepaid expenses and other assets on the consolidated balance sheets, and a liability of zero and $0.03 million, respectively, and is included in other liabilities on the consolidated balance sheets. The aggregate carrying value of the interest rate cap was zero on the balance sheet as of December 31, 2017 and December 31, 2016.

Hedge ineffectiveness related to cash flow hedges, which is reported in current year income as interest expense was $0.1 million and $0.3 million of income for the years ended December 31, 2017 and 2016, respectively. Hedge ineffectiveness was not significant for the year ended December 31, 2015.

Additionally, the Company has entered into total return swaps that effectively convert $256.6 million of mortgage notes payable to a floating interest rate based on SIFMA plus a spread. The total return swaps provide fair market value protection on the mortgage notes payable to its counterparties during the initial period of the total return swap until the Company's option to call the mortgage notes at par can be exercised. The Company can currently call all of the total return swaps with $256.6 million of the outstanding debt at par. These derivatives do not qualify for hedge accounting and had a carrying and fair value of zero at both December 31, 2017 and 2016. These total return swaps are scheduled to mature between September 2021 and November 2022. The realized gains of $10.1 million, $11.7 million, and $5.7 million as of December 31, 2017, 2016, and 2015, respectively, were reported in current year income as total return swap income.